Based on the measurement of electrical parameters of the rock, a detailed study employing resonant cavity method has been carried out by simulation, according to the electrical characteristics of rocks. The performance of the conventional resonator has been improved by designing a miniaturized measure instrument, which is convenient to be carried out and used. Then, the perturbation method along with the equivalent circuit method has been both employed to simulate this resonator. The relationship of electrical parameters and resonant parameters has been deduced. Furthermore, the exact relationship of them has been elicited by the method of fitting. The model has been tested by simulating, and the accuracy between equivalent circuit model and perturbation method has been compared. Measurement error using equivalent circuit model is under 5%. Finally, some materials are measured, and the deficiency and the improving methods are analyzed based on the built measurement system.