Abstract: In the process of processing, transportation, installation, operation and maintenance of transmission tower, due to the influence of extreme meteorological environment, bar deformation, construction quality and other factors, there is a problem of insufficient bearing capacity of tower structural members, which seriously threatens the safety of transmission. Based on the in-situ rectification project of N001^# tower in a 220 kV relocation line project of a Jiangnan station π access concentric station, the key technology research on the main material of in-situ rectification deformation of the tower is carried out. The field measured data measurement shows that the root opening of the transmission tower foundation and the height difference of the top surface of the foundation have exceeded the specified limits of Code for Construction and Acceptance of 110 kV～750 kV Overhead Transmission Lines（GB 50233—2014）. Fully considering the actual use conditions and on-site construction conditions of the tower, and carrying out accurate stress calculation and structural analysis of the deformed tower, it is judged that there is forced assembly during the construction of the tower, and the additional internal force value of the deformed main material reaches 24. 2%. In order to ensure the long-term safe operation of the line, combined with the local meteorological conditions, considering the long-term load of the tower, the stress analysis of the deformation of the local components of the tower under different working conditions is carried out, and the applicable boundary conditions of the deformed tower are set. An in-situ correction scheme for restoring the tower root opening and strengthening the deformed main material is proposed, which focuses on the hoop lifting and fixture connection cross reinforcement technology. The key technical points of in-situ correction of transmission line tower are summarized. The in-situ rectification project has been completed in 2019, and the rectification tower has been operating safely and stably for more than 3 years. This in-situ rectification and reinforcement scheme provides engineering experience and technical support for solving the same type of problems of transmission line towers.