To improve the alignment precision of laser beam and target for high power laser driving device in Inertia Confinement Fusion(ICF),several kinds of laser beam aligning methods,such as inside chamber direct alignment method, outside chamber direct alignment method, and indirect alignment method with Laser and Target Alignment Sensor(LTAS) based on optical conjugate principle, were induced and their advantages and disadvantages were analyzed. Then,the precision of the last method including the image measuring error,the errors introduced by protective glass of CCD, the movement errors of guides and the calibration error of Laser and Target Alignment Sensor(LTAS) was discussed. The experiments and precision analysis indicated that the laser beam aligning precision induced by LTAS is ±10 μm, which shows proposed LTAS can rapidly and exactly align the laser and target of large-scale laser driving device.