This paper gives a new definition, the Miss Distance Sensitivity to Target Maneuvers (MDSTM), which evaluates the robustness of the Terminal Guidance System (TGS) and gives the degree of exact miss distance caused by the inaccurate estimates of target maneuver. In this paper, the criterion of sensitivity analysis is the ratio of miss distance to target maneuver. The form of the TPN is investigated and then the GTPN guidance law is also proposed. Then, considering cases that the flight control system without dynamics and the dynamics characteristic can not be ignored, the MDSTM performance of TGS governed with TPN and GTPN for step acceleration target maneuvers are analyzed. Finally, the sensitivity analysis results of the system are listed in the paper, and the conclusions of how the effect the MDSTM were given in the end of the paper.