To intelligently evaluate the detectability of DSP early-warning satellite, a simulated scheme of system modeling for the process of satellite detecting is proposed based on the detection probability, the false alarm probability, the first instant when a target is captured and the minimum detection altitude. Through the assistance of STK, and the establishment of a series of models for the positioning parameters between satellite and missile, for the infrared radiation of missile target, the trajectory of missile, atmospheric background radiation and the noise of satellite detector, we constructed the simulated system for evaluating the detectability of DSP early-warning satellite. Some major findings were indicated when the system was applied in a simulation research. If the position relationship between satellite and missile remains constant and the weather condition is stable, the detectability of DSP early-warning satellite varies inversely as the detection probability of satellite and directly as the false alarm probability of satellite firstly, then keeps stable. If the detection probability of the satellite, the false alarm probability of the satellite and the position relationship between satellite and missile all remain constant, the detectability of the satellite within the wave band of 2.7 μm in clear weather is superior to that in cloudy weather. If the detection probability of the satellite and the false alarm probability of the satellite remain constant and the weather condition is stable, the detectability of the satellite for low latitude target is superior to its detectability for high latitude target.