Space gravitational wave detection is significant for further verifying the theory of general relativity and studying the formation and evolution of the universe. However, in space gravitational wave detection constellations, the interstellar laser links are distant, which puts new requirements on the pointing accuracy of laser precision pointing systems. To compensate for the non-conservative forces on the satellite platform to follow the motion of the test mass, this is usually achieved by a drag-free system utilizing microthruster actuation. However, while the drag-free system compensates for the external non-conservative forces, the perturbation of the microthruster, the measurement noise of the sensors, and the small adjustments of the platform's attitude and position may lead to the angular perturbation of the precision pointing system and thus reduce the pointing accuracy. Therefore, it is necessary to conduct modeling research on the mechanism of micro-perturbations of the drag-free system. Considering that the satellite platform may be affected by various micro-perturbations, including solar light pressure perturbation, temperature interference, and control system micro-perturbations, this paper models the micro-perturbations from three different aspects: mechanics, thermodynamics, and control. In the micro-perturbation dynamics modeling, this paper mainly considers the solar light pressure modeling and the dynamic modeling of the test mass micro-perturbation. Additionally, the modeling and analysis of the mechanism of high-order coupling effect micro-perturbations are carried out. For the solar light pressure modeling, this paper refers to the data of VIRGO to establish a solar light pressure perturbation model considering the influence of random fluctuations in solar light pressure. Since the test mass tracked by the satellite platform does not directly apply a disturbing force to the platform, but the small adjustments in position and attitude when tracking the test mass, as well as the control force applied by the actuator, can both cause disturbances to the precision pointing system. Therefore, dynamic modeling is performed for the test mass. In the part of high-order coupling effect micro-perturbation modeling, this paper conducts perturbation simulation analysis and compares it with the perturbation levels of the former two. Because the perturbation level of high-order coupling effect micro-perturbation is much smaller than the former two, this paper mainly considers the effect of low-order micro-perturbations in the micro-perturbation simulation analysis of the drag-free control system. In the part of micro-perturbation thermodynamics modeling, considering that changes in the orbit cause changes in external heat flow, leading to temperature fluctuations in the detection satellite. Thermoelastic deformation and interference can cause deformation in some structures of the satellite, resulting in optical axis pointing errors and affecting its pointing and tracking performance. Therefore, in this part, the impact of temperature fluctuations induced by solar heat flux on the laser precision pointing system is modeled and analyzed. In the part of control system disturbance source modeling, this paper mainly considers the disturbance modeling of the control system actuator, i.e., the microthruster, and the modeling of the measurement noise of the control system star sensor. Because different micro-perturbations have different response characteristics when transmitted to the target node, and there may be coupling effects between them while propagating in the satellite structure, the modeling of the perturbation transmission model of multiple micro-perturbations in the satellite structure has the problem of transmission coupling. Analyzing and calculating the transfer function of each micro-perturbation to the precision pointing system and simply superimposing the responses does not match the actual situation. In addition, considering that it is difficult to completely replicate the space environment on the ground, it is also difficult to directly analyze the coupling effects of multi-disciplinary micro-perturbations through experiments. Therefore, this paper establishes a micro-vibration transfer function model through finite element modeling. Subsequently, an integrated simulation framework for the micro-vibration of the drag-free system was established to deeply analyze the impact of the micro-vibration of the drag-free system on the laser precision pointing system. Through the integrated simulation analysis of multiple perturbation sources, the results show that under the open-loop condition of the pointing system, the angular response amplitude of the precision pointing mechanism is the largest around the Y-axis, but does not exceed 2.5×10^-7 rad, the angular response amplitude around the Z-axis is the smallest, which is below 4×10^-8 rad, and that around the Y-axis the angular response amplitude is around 1.5×10^-7 rad. In addition, it is noted that the angular response around the Z-axis oscillates within the range of -3.5×10^-8 rad, which is due to the dead zone nonlinearity of the microthruster control system. Subsequently, this paper analyzes the role played by each disturbance source of the drag-free system in this process. The simulation results of each perturbation source show that the effects of small adjustments in platform attitude and position and sensor measurement noise on the pointing system are relatively small. However, the microthruster perturbation during the operation of the drag-free system plays a major role in the angular perturbation response of the precision pointing system and can cause system resonance and modal vibration. In summary, when designing the control loop of the space gravitational wave detection satellite, it is necessary to consider the perturbation of the precision pointing system by the drag-free system and to suppress the microthruster perturbation.