When Dynamic Window Approach (DWA) is used in obstacle avoidance of blind-guiding robots, the contradiction which between the heading and velocity evaluation factors is not considered, resulting in, selecting the trajectory under certain road conditions, the not-timely collision avoidance, frequently direction changing, time-consuming planning and other issues in the planned path. To balance the relationship between the original three evaluation factors, the evaluation factor about the change of orientation is introduced into the function of path evaluation, which will suppress the excessive influence of a particular factor on the evaluation function under some specific circumstances, and to reduce unnecessary steering frequency of the robot. Experiments reveal that the actual required runtime of the planning path with the improved algorithm is reduced at average of 45.37% compared with that with the DWA algorithm, path planned with the improved algorithm can be planned advance to avoid obstacles with a smaller and continuous curvature. It can be obtained that the improved algorithm has a smoother trajectory and more timely collision avoidance, which can meet the comfort requirements of the blind-guiding robot's users.