For power amplifier module based on silicon based semiconductor devices, due to improper control of the amplifier's switching time and the slope of the rising or falling edges of the switch caused by the device physical structure itself, modulation of adjacent channel power(ACP)and adjacent channel transient power(ACTP) are poor, causing adjacent channel interference. Based on the silicon based semiconductor device power amplifier module in the digital two-way radio application, a new method was proposed creatively to optimize the amplifier gate bias circuit. The influence of the switching time of the amplifier and the slope of the rising and falling edges of the switch on ACP and ACTP was analyzed and deducted in theory. In practical application, the rising edge and the downward slope of the power amplifier switch were adjusted by properly adjusting the capacitance of the bias circuit and the series resistance of the power amplifier module of the two-way radio. The experimental results show that this can effectively improve the performance of ACP and ACTP, when the channel spacing is 12.5 kHz, the ACP and ACTP are less than -60 dBc and-50 dBc without affecting the output power and efficiency of the amplifier, it has certain practical significance and application value.