Semi-rigid joints have a significant influence on the internal forces and deformations of transmission towers. However, in traditional transmission tower structure optimization, semi-rigid joints are often oversimplified as hinge joints. To accurately evaluate the true response of transmission towers and rationally optimize their structures, this study focuses on transmission towers with semi-rigid connections. A finite element model for such towers is established using spring elements to simulate the moment-rotation relationship of semi-rigid joints. Furthermore, an optimization mathematical model and design scheme for transmission towers with semi-rigid connection are proposed, resulting in the development of a discrete optimization method for these structures. The optimization results show that the proposed method effectively reduces the consumption of steel in transmission towers while satisfying structural stress and deformation constraints, leading to cost savings and favorable economic benefits in engineering projects.