Abstract: In this paper, an evaluation approach of transmission transfer capability is presented by considering generation reliability and static security analysis. On the one hand, the minimal transmission transfer capability is calculated by using optimized convolution method with the precondition of ensuring system reliability, and it is compared with that obtained by traditional Monte Carlo simulation. On the other hand, after analyzing system power source, load and power grid structure, relative transmission accessing nodes and static security constraints are set, and the maximum transmission transfer capability is gotten through improving system load level and transmission transfer capability step by step. By taking regional power grid that is the planning scheme in 2020 as case analysis, the result shows that proposed optimized convolution method has higher efficiency with comparison with that of Monte Carlo simulation, and the calculated demand and scale of transmission transfer capability can prove the rationality of planning scheme from transmission transfer capability point of view.