对空间目标实际探测过程中，光电系统的探测能力不仅与其可探测信噪比有关，还与其所成图像的质量有关，即空间分辨能力有关。针对现有光电系统探测能力分析不足，提出了一种基于调制传递函数下的信噪比探测模型(MSNR)，给出了基于MSNR下的系统极限探测能力综合评估方法，实现可定量分析大气、像差、目标运动等对系统探测能力的影响；利用实测数据完成对MSNR模型的完善，对不同条件下光电系统的极限探测能力进行了仿真，仿真结果表明: 大气条件、系统像差、目标运动等条件对系统的探测能力影响明显，目标运动导致探测能力降低近1.0等星；该方法实现定量对光电系统的探测能力进行综合评估，可为系统优化设计与实际工作开展提供一定的科学依据。

In detecting process, the detecting ability is not only affected by the detecting signal-to-noise ratio(SNR), also by the quality of the detecting image, and the detecting ability evaluating method in existence is only based on the SNR. To offset the deficiency of the evaluating method in existence, a new evaluation on detecting ability of the electro-optics system is put forward, which combines the detecting SNR and system modulation transfer function(MTF), and it can also give the quantitative analysis of the effect of the atmosphere, the aberration and the motion. The new evaluating method was used to simulate an electro-optical system under different conditions. The simulation indicates that the atmosphere, the aberration and the motion can affect the detecting ability seriously, and the motion reduces the detecting ability nearly 1 magnitude. The detecting ability can quantitatively studied with our method, which provides a scientific basis for optimization design of electro-optical systems.