In orbit capturing and real-time monitoring the status of distant dimmer space targets is of vital importance for space safety. However, when the sensitivity approaches 14 magnitude, the intensive stellar population, the stellar scattering light will reduce the detection efficiency greatly, resulting in a limited detection range and ability. To solve this problem, a simple method for space object capturing, classification and online tracking was presented, synchronously eliminating the dense background stars and sequentially extracting the possible space targets, utilizing the regular motion of a moving object in a short timespan. Ground simulations and tests validate the effectiveness and accuracy of the method. It seems that this method can also be used as a basic function for deep space projects, such as asteroid and planet exploration in the solar system.