For achieving the greatest sensitivity, numerical simulation is proposed to optimize the parameters of light force accelerometer (LFA). Firstly, the basic principle of the LFA is analyzed, and the mathematical model is established to describe the axial and radial optical trapping forces on microspheres in the fundamental mode Gaussian laser beam. Secondly, the axial and radial optical trapping forces applied on Mie spheres are simulated to obtain the optimal parameters of open-loop LFA. Results show that the sensitivity can reach 10³μm/g. Finally, the LFA system is proposed based on the closed-loop scheme with dual beams. This can provide reference for the design and fabrication of LFA in future.