During regression testing, when software is retested after some modifications, the size of test suite grow significantly.Thus the costs of regression testing increase dramatically. To reduce the cost of regression testing, regression test suite reduction must be carried out. Traditional methods reduce the faults detection capability either. The new method take into account the three factors of the test coverage, test execution cost and fault detection capability. The simulation results show that the method is effective in test suite reduction and ensuring fault detection capability after test suite reduction.