Based on the theory of light wave propagation in the atmosphere, the imaging process of a space-based optical system in a slant atmospheric path is simulated, the influence of atmospheric turbulence on imaging quality under different conditions is analyzed, and the simulation results are compared with theoretical ones. The simulation results show that when the system aperture is smaller than the atmospheric coherence length, the resolution increases significantly as the aperture enlarges. While the system aperture is larger than the atmospheric coherence length, the resolution tends to be stable gradually as the aperture increases, and the optimal aperture is about 2r0 (r0refers to the atmospheric coherence length). Through the simulation of structure constant models with different refractive indexes, it can be seen that as transmission distance increases, the minimum resolvable length improves gradually. However, when the transmission distance reaches 50 km, the length tends to be stable. Therefore, when the transmission distance is below 50 km, atmospheric turbulence has a great impact on the imaging quality of the optical system. In addition, weak atmospheric turbulence will affect the ground resolution of the optical system at a degree of 2-3 cm, while strong atmospheric turbulence will affect that at a degree of 7-10 cm. Furthermore, the high-altitude turbulence in the tropopause can greatly affect the imaging quality. If the influence of the high-altitude turbulence is ignored, the resolution can be improved by about 1.4 times.