Based on the working environment and requirements of high temperature coal furnace slag-flat operation, this study combines six axis industrial robot, robot rail and rake-bracket structure to form an 8 dof redundant heterogeneous robot system to realize the automatic slag-flat pushing work of high temperature coal furnace. Through the system to the whole redundancy heterogeneous robot inverse kinematics analysis: due to the limitation of high temperature coal stove opening structure, cause there are many invalid solution for inverse solution, this research puts forward a kind of obstacle avoidance based on rake rod movement joint optimal inverse solution algorithm, improves the speed of the robot system inverse solution and efficient. Through simulation experiments show that the algorithm can improve the solution efficiency of this redundant heterogeneous robot system, reduce the invalid solution.