Loose bolts in tension clamps are among the major causes of safety hazards such as hardware detachment and arc discharge in high-voltage transmission lines. To address the low efficiency and precision of bolt-tightening operations performed by existing transmission line inspection robots, an improved trajectory planning and tracking control method is proposed. First, trajectory planning is carried out using a 3-5-3 polynomial interpolation approach. A “velocity pause” mechanism is introduced, and the trajectory is optimized using a multi-strategy improved particle swarm algorithm incorporating Levy flight, achieving both minimal trajectory time and smooth motion. Then, a controller combining global nonsingular terminal sliding mode control with a super-twisting algorithm is designed. Simulation results verify that the proposed method improves system response speed while effectively suppressing chattering. Finally, the proposed trajectory planning and control scheme is further verified through physical experiments, demonstrating significant improvements in operation efficiency and tracking accuracy of transmission line robots during bolt-tightening tasks.