In the mobile sensor networks(MSN), the existing target tracking control strategies have shortcomings in preserving topology connectivity and decreasing power consumption. Therefore, a target tracking algorithm based on the flocking-based mobility control algorithm is proposed. Firstly, the target is assumed to be observed by a small fraction of mobile sensors in the networks, which takes important role on reducing power consumption. Then, the connectivity-preserving and collision-avoiding flocking algorithm enables all mobile sensors to track the target utilizing the states of target which are estimated by the small percentage of mobile sensors using Kalman-consensus filtering. Finally, simulation results show the effectiveness of the proposed control scheme.