Playfield detection is a key technology for content analysis in sports video, on which many semantic clue mining methods rely. However, shadow produced by substantial illumination change causes the general detection method fail and degenerate the performance of the following processing based on it. This paper presents a method for detecting playfield, which can find shadow region under the guidance of the intrinsic image proposed by Finlayson. Firstly, this method automatically finds the dominant color; secondly, according to the dominant color and the intrinsic image, it determines the playfield colors. At last, we apply it to player tracking in soccer video. Experimental results show that the proposed method can handle the problem brought by shadow and improve the performance of the application based on it.