In view of the lack of optimization method for the s hape design of energy leakage hole of explosion-proof high voltage cable joint，this paper uses the finite element calculation method coupled with temperature field，fluid field，and displacement field to simulate the explosion process inside the joint，and puts forward the design principle of optimizing the shape of the energy leakage hole in the copper shell of explosion-proof cable joint.An optimization method that uses the tangent value of the convergence angle of the ejected airflow from the energy leakage hole as the key parameter is proposed.Through the examples，the airflow velocity at the edge of the three typical energy leakage hole shapes is decomposed into three directional velocity components，and the maximum and average values of the three velocity components are obtained.The trajectory of gas ejection of the energy leakage hole in the copper shell of a 220 kV explosion-proof high voltage cable joint with different opening shapes，is calculated.According to the design method of the shape of the energy leakage hole，it is obtained that when the shape of the energy leakage hole is circular，the gas ejection is the most restrained，and the explosion-proof effect is the best.The design ideas and important parameters according to the optimal design of the energy leakage hole of the explosion-proof high voltage cable joint can provide valuable guidance.