For the service transmission tower with long operation time or expansion and reconstruction requirements, the insufficient bearing capacity of certain components leads to the transmission tower unable to meet the higher design requirements. Therefore, it is necessary to study the reinforcement measures of angle steel components to effectively improve the bearing performance of transmission towers. Taking the typical angle steel in transmission tower as the research object, a non-destructive reinforcement method for transmission tower was proposed. In this method, bolts and fixtures are used to form a composite reinforcement component by combining the original component and the reinforcement component. The composite component does not cause damage to the original component, and the structure is simple while the application is wide. A more detailed numerical model of composite members was established to study the influence of slenderness ratio of original members, fixture spacing (number) and steel properties on the reinforcement effect of composite members, and the calculation method of compressive bearing capacity of composite members was deduced. The results show that the proposed reinforcement method has remarkable effect, and the reinforcement level is up to 56.34%. The slenderness ratio of the original component has obvious influence on the lifting level of the composite component, and the lifting effect of the composite component is gradually obvious with the increase of the slenderness ratio of the original component. When the number of fixtures is odd and the spacing of fixtures is less than 750 mm, the reinforcement effect of composite members is optimal. Steel properties of reinforced members have marginal effect on compressive bearing capacity and ductility of composite members. The proposed calculation method of compression bearing capacity of composite members is in good agreement with finite element simulation.