The lightning protection tests for the radome system of the Y7-200A aircraft of China are presented in the paper. The radome system is composed of the radome, the diverters, the simulated radar antenna and a 0.5m long metal structure, which connects with the radome and simulates a part of the aircraft body. The test facilities and the test results are introduced. Based on the tests, the radome system performance preventing lightning destruction is improved by optimizing the diverters . Finally, the optimized radome with the diverters passed the ground simulated lightning tests successfully by the chinese CCAR25 and the standard of lightning protection of aircraft HB6129-87.