Aiming at the problem of leak detection, hollows and false targets in the traditional frame difference algorithm, an improved frame difference algorithm is presented. The effect of moving target detection is experimented and analyzed in several common color spaces, selecting excellent color channels to build hybrid color space CbVb* for moving target detection. In order to make full use of the correlation information among frames, seven frame difference algorithm is presented to calculate moving target frame difference in time domain according to the pixel changing characteristics of CbVb*, and edges of moving target in gradient domain is obtained by using Canny operator with adaptive threshold. Then, frame difference in time domain combines with target edges in gradient domain, and the combined information is carried on corrosion and expansion processing to get the final detection results. The experimental results show that the improved algorithm can more accurately detect moving targets, and have good robustness, adaptability and real-time performance.