In this paper,a method for detecting dim small moving infrared target based on gray morphological accumulation and SUSAN algorithm is proposed.First,a Butterworth high pass filter is used to process the original infrared image,thus an image containing some noise and target points is obtained.Then,the ratio of signal to noise of the image is further enhanced through the multi-frame accumulation in gray morphology.Finally,the SUNSAN detection algorithm is used to process the image which is multi-frame accumulated and detect the true target.In order to improve the real time performance of small target detection,a hardware structure based on FPGA and DSP is given.The experimental result shows that this method can eliminate background and depress noise effectively and hence detect the moving small infrared target accurately and effectively.