Since the number of switching hops are severely restricted by the insertion loss of optical switches in an optical packet switching network. A two-cascaded optical gain switch based on four-wave mixing nonlinear effects in semiconductor optical amplifiers was investigated. By using this method, the quality of output signal from the optical switching will be improved as well as achieving the shape regeneration and power compensation, which means the limitation could be overcomed. The result from the OPTISYSTEM simulation platform shows that, in an optimization system, the maximum of the gain is more than 25 dB, meanwhile the bit error rate and Q factor could gain a high promotion (from 10－5 to 10－18 and 4.16 to 8.71, respectively), with the pump wavelength located at the center wavelength of the signal light within ±4 nm, the power ranging from 3 dBm to 15 dBm. This optical gain switch system will have great application prospect in optical packet switching network with multi-hops.