Engine thrust cutback can be applied to flyover noise certification, sound level varies with different thrust cutback flight paths, and there exits the optimized noise level with thrust cutbacks. The noise level corresponding to typical points on each flight path with different thrust cutback point can be derived from noise-powerdistance(NPD) database. According to the optimization thrust cutback conditions, the optimized flight path and its corresponding noise level can be determined. As an alternative method for flight test, the optimization method with thrust cutback can save the time and cost of noise certification.