The embodiment of the invention provides an obstacle avoidance path planning method based on improved mechanical arms D* for achieving dynamic obstacle avoidance path planning of mechanical arms. The method comprises the steps that all components of the mechanical arms and obstacles in the environment are converted into a cuboid envelope through a hierarchical bounding volume method, and a relevant algorithm is designed for achieving fast collision detection between the mechanical arms and between the mechanical arms and the environment; according to spatial mechanical arm characteristics, a path search algorithm based on a heuristic function is obtained; obstacle avoidance path planning applied to seven-freedom-degree mechanical arms D* is improved, and dynamic obstacle avoidance path planning of the seven-freedom-degree mechanical arms is completed. According to the technical scheme, the method is used for achieving dynamic obstacle avoidance path planning of the seven-freedom-degree mechanical arms based on the improved mechanical arms D*.