For the target losing problem caused by shadows during target tracking，an outdoor target tracking method is proposed based on the intrinsic value of a shadow image. A new method is proposed to calculate the intrinsic value of a shadow image based on the derivation of a linear relationship between the pixel values inside and outside the shadow areas. The sequence images are transformed into intrinsic images，which are insensitive to shadows，and then a mean shift tracker is employed to locate the object in the image. Our method doesn't need any of the camera's parameters，and has a high calculation rate. Object-tracking experiments have been done on sequence images with shadows． Compared with other tracking methods，our method has a higher tracking accuracy，and the calculation speed can achieve real-time requirements. The experimental results validate the performance of our method.