ViBe background subtracted algorithm deals with pixels based on RGB color space. So when the light suddenly changed, a large of background area will be misclassified as moving foreground. In addition, ViBe algorithm considered a lot of the moving background pixels to be foreground in the scene. To solve these problem, this paper proposed algorithm which combined with (r,g,I) normalized color space. The experimental results show that the improved algorithm can reaches the more robust extraction for foreground at the abrupt changes of light. At the same time, the improved algorithm has a better effect on detecting the moving background pixels in the scene.