Abstract: This paper proposes an efficient parameter extraction algorithm for GaN high electron mobility transistor(HEMTs) small signal equivalent circuit model, which combines parameter scanning and iteration methods, to solve the problem of error accumulation in conventional methods. By using the iteration process, the algorithm each time uses more accurate element values, which makes the results faster and easier become optimal. The 19 elements small signal equivalent circuit model of GaN HEMTs is used to validate the proposed algorithm, and the results show that the calculated S-parameters agree well with the measured S-parameters within the frequency range of 0.1 GHz to 40 GHz.