An autonomous approach for detection and tracking of moving object with a mobile robot using laser scanner is presented in this paper. Firstly, ranging data of environmental objects from laser scanner are clustered according to the dynamic clustering method of k-nearest neighbors. Then, the movement parameter of clustering objects is computed by local grid map matching. At the same time, the movement compensation of mobile robot is estimated. After obtaining the moving object, particle filter (PF) with the improved proposal distribution is adopted to track moving object so as to get the movement condition of the object. At last, experiments with the mobile robot designed by us are implemented and the validity of this approach is verified.