To resolve the problems in real time detection of moving dim small target, such as system dithering and low signal noise ratio, a new method based on mathematical morphology filtering, the continuity of target's intensity and hypothetical test according to the characters of moving dim small target is presented. High-pass filter based on mathematical morphology can suppress clutters and emphasize the target-like peaks. The continuity of the target's photic intensity can be used to identify target effectively. Hypothetical test has attractive result to resolve the problems of target missing and new target occurring. The algorithm has been realized on the TMS320C6201 digital signal processor (DSP), and the experiment results show that the method of detecting the moving dim point target is efficasious when SNR is about 2