In the view of the problems of slow convergence speed and easy to fall into local optimum when polishing robot path planning in complex space，a path planning method for polishing robot based on improved ant colony algorithm was proposed.The polishing robot D-H connecting rod model was established，forward and inverse kinematics analysis and calculation verification were carried out;an improved pheromone update method was proposed,the new adaptive calculation method was applied to the state transition rule，and by introducing the damping coefficient ξ,the heuristic information function was improved;a simulation experiment was carried out in MATLAB to find the best parameter group for the improved ant colony algorithm.The results show that compared with the basic ant colony algorithm，the shortest path length from the starting point to the end point of the proposed improved ant colony algorithm is reduced by an average of 14.3%，and the iterations number is reduced by an average of 55.3%;combined with the tool position of the grinding robot,the shortest and smooth path can be obtained.The proposed method can be used to effectively solve the problem of 3D path planning of the grinding robot.