An X-band four-way combined GaN solid-state power amplifier module is fabricated based on a selfdeveloped AlGaN/GaN HEMT with 2.5-mm gate width technology on SiC substrate.The module consists of an AlGaN /GaN HEMT,Wilkinson power hybrids,a DC-bias circuit and microstrip matching circuits.For the stability of the amplifier module,special RC networks at the input and output,a resistor between the DC power supply and a transistor gate at the input and 3λ/4 Wilkinson power hybrids are used for the cancellation of low frequency self-oscillation and crosstalk of each amplifier.Under V_(ds)=27 V,V_(gs)=-4.0 V,CW operating conditions at 8 GHz,the amplifier module exhibits a line gain of 5 dB with a power added efficiency of 17.9%,and an output power of 42.93 dBm;the power gain compression is 2 dB.For a four-way combined solid-state amplifier,the power combining efficiency is 67.5%. It is concluded that the reduction in combining efficiency results from the non-identical GaN HMET,the loss of the hybrid coupler and the circuit fabricating errors of each one-way amplifier. An X-band four-way combined GaN solid-state power amplifier module is fabricated based on a self-developed AlGaN / GaN HEMT with 2.5-mm gate width technology on SiC substrate. The module consists of an AlGaN / GaN HEMT, Wilkinson power hybrids, a DC-bias circuit and microstrip matching circuits. For the stability of the amplifier module, special RC networks at the input and output, a resistor between the DC power supply and a transistor gate at the input and 3λ / 4 Wilkinson power hybrids are used for the cancellation of low frequency self-oscillation and crosstalk of each amplifier. Unit V ds = 27 V, V gs = -4.0 V, CW operating conditions at 8 GHz, the amplifier module exhibits a line gain of 5 dB with a power added efficiency of 17.9% and an output power of 42.93 dBm; the power gain compression is 2 dB. For a four-way combined solid-state amplifier, the power combining efficiency is 67.5%. It is said that the reduction in combining efficiency results from the non-identical GaN HMET, the loss of t he hybrid coupler and the circuit fabricating errors of each one-way amplifier.