Abstract: The position of drill pipe loading and unloading by mine drilling robot will change with the attitude adjustment of the host machine, and obstacles are present in the loading and unloading path of drill pipe. Therefore, there is a problem of obstacle-avoidance trajectory planning with variable targets in the loading and unloading of drill pipe. For this reason, the DH parameter table was created according to the performance parameters of the explosion-proof 6-DOF manipulator, and the function relation of the change in loading and unloading position of drill pipe before and after the attitude adjustment of the 3-DOF host machine was proposed. Besides, the collision detection model of the drill pipe loading and unloading system was established using the convex envelope and simple geometry, which could judge the collision by Euclidean distance. Herein, a three-stage obstacle-avoidance trajectory planning method was proposed for the loading and unloading of drill pipe. Specifically, linear planning in Cartesian space is adopted for the first and third stages, the second stage is planned with the polynomial interpolation algorithm in joint space, and the obstacle-avoidance problem can be solved by adding transition points. In addition, study was carried out on the minimum impact obstacle-avoidance trajectory planning algorithm based on the seventh-degree polynomial interpolation. The simulation analysis shows that the joint angle, angular velocity, angular acceleration, and angular jerk are continuous, but the absolute peak value is enormous and the path is long. Thus, further study was conducted on the impact-optimal obstacle-avoidance trajectory planning algorithm based on the improved bidirectional RRT algorithm, B-spline path optimization, and seventh-order polynomial interpolation, which could guarantee the continuity of joint angle, angular velocity, angular acceleration and angular jerk with short path and the peak value of angular jerk reduced by 98.2% according to the simulation analysis. Moreover, teaching test was implemented to verify the feasibility of the impact-optimal obstacle-avoidance trajectory planning method in obstacle avoidance and loading trajectory of drill pipe. The running curves and moving paths of each joint of the manipulator are highly similar to the simulation results. The research results could provide a reference for the control program of the drill pipe loading and unloading system of drilling robot and have important significance for improving the intelligence of drilling rig.