Abstract: To improve accuracy of dynamic wirless sensor networks in applications of target tracking,intrusion detection,gesture measuring,enviorment minitoring and control and so on,the paper proposed a location mechanism for mobile nodes.Probability grid scheme was used to determine probability distribution of mobile nodes in monitoring area.Probability distribution of mobile nodes at the studying moment was estimated by discret samping set with weight.Method of statistical experiment was used to complete self-location of mobile nodes.The location mechanism needn’t prior knowledge of wireless sensor networks and hypothesis of mobile directions of nodes.High accurate of node location can be achieved using anchor nodes with low density,which can utilize mobile charaitnitics of dynamic nodes effectively and decrease influence of uncertain factors.The simulation results verified the validity of the location mechanism.