Abstract: Open capacity evaluation is one of the main tools for distribution network planning and operation, which has important reference value for improving the reliability level of distribution network and formulating upgrade and reconstruction schemes. In order to overcome the shortcomings of traditional open capacity evaluation model which are oversimplified and unable to deal with multi-tie feeders effectively, a novel open capacity evaluation model considering N-1 security criteria and network reconfiguration was established. The proposed model considered both the power flow constraints under normal conditions and the switch operation constraints under fault conditions, and thus had the advantages of high quality of the solution and feasible calculation results. To solve this model, a generalized Benders-dichotomy approximation bilevel hybrid algorithm was proposed. The algorithm used the idea of upper layer approximation, lower layer checking and double layers interaction to continuously shrink the solution space in an alternating iterative manner until the optimal solution was obtained. The test results of 22-node and 70-node systems verify the correctness and effectiveness of the proposed model and algorithm.