Abstract: In order to solve the problem of insufficient high-frequency accuracy due to the lack of characterization of electromagnetic interaction in the traditional model, a small-signal equivalent circuit model and high-frequency equivalent noise circuit model with parasitic coupling effect is proposed by taking the Indium phosphide high electron mobility field-effect transistor (InP HEMT) with excellent high-frequency characteristics as an example. Firstly, the mutual inductance element between gate and drain is introduced to simulate the parasitic coupling effect caused by electromagnetic interaction at high frequency, and the modeling method combining electromagnetic simulation and direct parameter extraction is used to establish a small signal equivalent circuit model. Then, based on the small signal model, the high-frequency equivalent noise circuit model is established through the extraction method of correlation noise matrix and noise parameters. The experimental results show that in the frequency band of 500 MHz−50 GHz, the maximum error of the S parameter is less than 3%, and the four-noise parameter is increased by about 2.45% compared with the traditional model, and the influence of the parasitic coupling effect on the high-frequency performance is evaluated from the small signal current gain (|h₂₁|), unilateral power gain (U) and minimum noise figure (F_min).