Abstract: A simple and effective method for establishing lumping equivalent circuit model of onchip spiral inductors is introduced in the paper. Then an idea of equivalent substitution for compensation with capacitances and inductors is proposed and a wideband circuit with nine parameters is realized. By simulating the structure of air bridge across type and dielectric isolation underpass type in ADS respectively, the equivalent model has good fitting effect on Sparameters, effective inductor values and Qfactors from 26 GHz to 40 GHz. Therefore, it can provide fast and feasible scheme for parametric modeling of onchip spiral inductors.