In recent years, an increasing number of steel latticed transmission towers collapsing under strong winds has been observed. Based on the finite element model of the actual collapsed tower in 2021 China, static nonlinear buckling analysis was performed to estimate the ultimate bearing capacity and the most vulnerable members of the tower in this paper. Considering the moment caused by the semi-rigid connection between the leg and diagonal members, the press-bending member stability state assessment method is developed to identify the weak locations in the transmission tower. The results show that the collapse wind speed is 35.10 m/s and the primary failure member is the diagonal member in the first panel featuring redundant members. And the main member in the lower panel of the failed diagonal member can serve as the secondary weak member. The weak position corresponds to the actual failure. The press-bending state assessment method of diagonal members could effectively analyze the capacity and vulnerable members of towers, which can serve as a reference for structural failure analysis.