A pre-selected minimum distance index is presented considering the real-time performance of dynamic obstacle avoidance for redundant robots. The OBB (oriented bounding box) is applied to modeling robot, and safe links are removed by intersection test before calculating real-time distance. The real-time minimum distance is calculated by local mapping based distance calculation method according to the coordinates of objective points. Based on that, avoidance factor and escaping velocity related to minimum distance are built and then mapping matrix in zero space of redundant robots is utilized to accomplish obstacle avoidance path planning. Finally, the validity and efficiency of pre-selected minimum distance index for dynamic obstacle avoidance are manifested by simulation. Compared with traditional path planning methods, the overall planning time is reduced by 15.5%.