To address the issues of unstable motion of the robotic manipulator and frequent collisions with line fittings caused by frequent start-stop actions of the joints during obstacle negotiation,this paper proposes a collision-free line grasping trajectory planning method based on blended seventh-order non-uniform B-spline curves. First, an obstacle negotiation model for the robot is established, describing the mapping relationship between the pose of the walking wheel assembly and the joint space coordinates. The collision-free regions in the joint space are determined based on the principles of obstacle negotiation, and selection rules for collisionfree intermediate path points are developed. Second, seventh-order non-uniform B-spline curves are employed to fit the intermediate path points, constructing a collision-free trajectory with high-order continuity and controllable boundaries. Finally, co-simulation using Adams and Matlab, combined with the Non-dominated Sorting Genetic Algorithm(NSGA-II) algorithm, is performed to optimize the manipulator′s end-effector time and impact for the obstacle negotiation trajectory. The results demonstrate that the proposed method effectively avoids collisions with line fittings during obstacle negotiation and line grasping. Additionally, the acceleration and jerk variation curves of all joints are smooth without sharp peaks or abrupt changes. Compared to the linear-polynomial trajectory interpolation method, the proposed approach reduces the acceleration, jerk, and average jerk of the telescopic joint by 18.1%, 83.01%, and 78.32%, respectively, resulting in smoother robot motion and enhanced safety during obstacle negotiation.