Abstract: To solve the localization problem of unmanned ground vehicle when the signals of GPS are susceptible to be disturbed,a window constrained Markov localization method was proposed. The scope of state space was constrained when Markov localization was taken within the window. The windows position can be determined initially refer to landmarks built in the map, and moved with vehicles movement. This method can reduce the amount of calculation and does not rely on satellite positioning system besides initial time. The positioning accuracy and real-time performance are testified on a full-sized unmanned ground vehicle.