Abstract: The invention relates to an AlGaN/GaN HEMT small-signal model and a method for extracting parameters thereof. According to the AlGaN/GaN HEMT small-signal model of the invention, based on a conventional AlGaN/GaN HEMT small-signal model, a first coplanar waveguide capacitor (I) between a gate and a source and a second coplanar waveguide capacitor (II) between the gate and a drain are added in a parasitic unit. Since an AlGaN/GaN HEMT device and a coplanar waveguide device have similar structures, by introducing the first coplanar waveguide capacitor (I) and the second coplanar waveguide capacitor (II) under a high-frequency condition, that is, considering the fact that the coplanar waveguide effect of the AlGaN/GaN HEMT device will introduce additional parasitic capacitances, the working state and device characteristics of the AlGaN/GaN HEMT device can be reflected more accurately, and the accuracy of the device model is improved.