In order to meet the needs of in-situ grinding repair of aero-engine blade, a simple and stable in-situ blade grinding robot model was designed. The kinematic model of the manipulator is established by using the D-H method. The inverse kinematics was solved by a specific algebraic method, and the analytic relationship model between the spatial pose parameters at the end of the grinding head and the joint variables of the in-situ blade grinding robot was derived. On this basis, the trajectory planning simulation of the robot model is simulated by Matlab, and the continuous and smooth displacement, angle, velocity and acceleration curves of the robot are obtained. The results show that the established kinematic model and the analytical relationships of each joint motion parameters obtained by the inverse solution are suitable for the trajectory planning of the in-situ blade grinding robot, which provides the basis for the control planning of the in-situ blade grinding robot and lay the foundation for the implementation of the motion control of the robot.