A modeling method of GaN-HEMT small signal equivalent circuit based on poles and residuals is proposed. Firstly, the poles and residuals of the accurate GaN-HEMT small signal model based on rational function are established by using vector fitting algorithm to reasonably fit the whole wideband measurement Y parameter of the device. Then, according to the different residual properties, the equivalent circuit model to realize the residual is discussed. Finally, a second - and third-order small-signal equivalent circuit model is established using poles and residuals. ADS software simulation verifies that the model has higher accuracy. The results show that the average relative error of S-parameters of the model is less than 1%, which is much lower than the traditional model. The problem of large error of traditional small-signal equivalent circuit model at high frequency is solved effectively. The proposed small-signal circuit model belongs to the research method of mathematical fitting model in essence, which is highly robust and can be applied to other similar transistors to improve practicability.