Abstract：Path planning in unstructured environment is one of the most active problems on research field of autonomous mobile robot. some planning methods has been empoldered and applied successfully in this field, for example, artificial potential field, fuzzy logic algorithm, genetic algorithm, and so on .thereinto, artificial potential field is the most effective method,, but the traditional artificial potential field has several problems, such as oscillation, tracing speed falls while robot approaching. For solving these problems, some improvement has been done to traditional artificial potential field, velocity potential field has been brought into traditional potential field, a new potential field function have been designed, and a strategy of path planning has been planned. Many simulations on path planning with new potential field and path planning strategy have been done in Matlab. Simulation results about dynamic target tracing, multi static obstacles and dynamic obstacle avoiding have been given in this paper. The results of simulation have verified that robot can adjust its velocity to escape from obstacle, and move to immobile target quickly, or track dynamic target synchronously.