Summary: This paper investigates a dynamic target-assignment problem. A close-loop integrated frame for target-assignment is proposed novelly which incorporates the kinematics between flight vehicles and targets. Based on an integral performance index which represents the energy cost, the optimal switching assignment-plan is obtained. Considering the configuration variation introduced by a switching assignment-plan, an \(H_\infty\) guidance law with switching-target is proposed which underlays a dynamic assignment process in cooperative tracking. Simulation results are given to show the effectiveness of the proposed guidance-law and the switching-plan for target assignment.