According to a space object color temperature measurement technology, a method for selecting optimal waveband and improving temperature resolving power and sensitivity of a space object detection system is proposed. Comparing the radiance values of a space object at different wavelengths, the relation between the homochromatic radiance and the wavelength and temperature of a standard blackbody is deduced. A mathematic model for measuring the temperature of a space object is established. Thus, the negative influence of the emissivity on temperature measurement is avoided. In addition, a mathematic model for optimizing the waveband is established. By analyzing the relation between the temperature resolving power and sensitivity and the detection waveband, the optimal detection band is selected for the system and its temperature measurement accuracy is improved. This waveband selection based on an infrared system is simulated. The result shows that when the bandwidth of 60 nm is selected in the range from 8.0 to 8.5 μm, the detection system has its temperature resolving power up to 0.07 K for a space object with a temperature of 200 to 300 K. Its temperature resolving power and sensitivity are increased by 0.079 and 0.113 respectively. The waveband optimization is very useful for the improvement of the temperature resolving power and sensitivity of a space object detection system. This work can provide fundamental support for the development of space object detection and recognition equipment.