An improved dynamic programming algorithm was presented to detect space small targets from sequence images. Firstly, the development and current situation of the dynamic programming algorithm used in small target detections were introduced. As the defocus was used to process commonly a project to obtain the sub-pixel center of a target,the recursive equation of score function was improved.A multi-point accumulation algorithm with direction weight was presented to replace the single-point accumulation in an original algorithm, and the original multispeed plane calculation was also simplified. Finally, the key processes including state initialization, constant false alarm rate threshold and track data structure were discussed. The analysis indicates that the computational complexity has reduced about 50% as compared with that of original algorithm. Experimental results also indicate that targets can be detected in 5th frame with the multi-point algorithm, while a number of fake tracks are found until the 10th frame with the original algorithm. Furthermore,the score SNR of 20 tracks with maximum score in the 5th frame of multi-point algorithm is 0.87 higher than that of original algorithm. The multi-point accumulation algorithm with direction weight is able to reduce the false alarm caused by a speckle noise efficiently and to raise the detection ability of dynamic programming.