The real-time detection and surveillance of space targets are primary functions of space surveillance system. On account of abundant infrared radiation of the electronic and electromechanical equipments inside satellites, spacecraft, etc., the infrared characteristics of space targets will be very obvious in the cold astrospace background. Therefore, using spaceborne IR detection system is very beneficial to space object detection, especially in the absence of any significant atmosphere. The key characteristic of spaceborne IR system is passive measurement principle, but not requiring direct sun illumination. This is very proper for the purposes of space control requirements. This paper has theoretically determined the feasibility of the spaceborne IR detection system in using infrared radiation characteristics of a space object and IR imaging sensor to locate and recognize object. According to the requirements of an IR imaging system to modulation contrast, signal-to-noise ratio (SNR) and image size of space object, the paper has discussed infrared radiation characteristics of space object and background, the structure of the system and primary factors which can affect operation range of the system. Results indicate that such parameters as principal design wavelength, spectral band and pixel size of receiving sensor, focal length and aperture diameter of receiving optics system and so on can determine scale, capacity and practicability of detection system. With a 150mm aperture, 800mm focal distance and 13μm IR CCD imaging pixel dimension, the system could detect a space object with size of 10 m and distance of 200 km. The imaging point of this object would occupy 3×3 pixels point.