In order to study the influence of satellite attitude variation on the detection ability of the satellite photoelectric imaging system, the targets in 0.38~0.78 μm spectrum of visible light radiation are calculated. The visible light reflectance model of the space-based optical observation is established on the basis of basic radiation theory. According to the geometric structure and material properties of the target, the influence of attitude variation on the area of effective incident section is analyzed. The formulas of the signal-to-noise ratio (SNR) and detection distance are derived, the influence of attitude variation on the detection capability is numerically simulated. The calculation results indicate that when the attitude changes over a period of time, to the 2.2 m×2.7 m solar panel, the maximum difference of SNR and detection distance can reach 101 and 105 km respectively with strong directionality, and to the satellite with 12 m high and 4 m diameter, the maximum difference can reach 102 and 106 km respectively. Attitude variation has a significant impact on the detection ability.