According to study of the characteristics of ray radiation from nuclear explosion, the detection system of nuclear explosion ray radiation based on high speed CMOS image sensor was analyzed in the theory and the structure. To meet the practical requirement, the high speed CMOS image sensor was used to make the photoelectric sensor and the high speed image processing system about DSP was adopted to make the detection system. The detection principle of nuclear explosion was analyzed based on image processing and the measuring error caused by atmospheric transmission was calculated. The author devised the program of algorithm for image processing. The simulation experiment indicates that the system can detect some parameters accurately, like equivalent, angle of pitch and distance. Compared with the conventional method, it has relatively high accuracy as well as good stability and reliability. Besides, it is easier to operate. The experimental result indicates that performance of the system achieves the expected goals.