The observation field of view of space camera in geosynchronous orbit is seriously affected by stray light, so it needs to be quantitatively analyzed. Aiming at the visible channel of the camera, the earth-reflected stray light is studied. The equivalent surface-source integration method is used to calculate the signal-to-noise ratio when observing the 6.5-magnitude star in the visible channel, and the calculation result is compared with the laboratory and on-orbit test data (the average error is less than 15%). The results show that the accuracy of the simulation calculation is high.