Abstract: Based on the experiment of the steady state characteristic of the traditional RC series circuit and combined with the relevant contents of electromagnetic theory courses，we propose the experimental scheme design of steady state characteristics including the second order RC filter circuit. The amplitude-frequency and phase-frequency characteristics of the first order and the second order RC filters are compared and analyzed. This experiment is very helpful to students to understand the principle of filtering，and to master the knowledge of the Kirchhoff equations in the AC circuit.

Key words: RC circuit, filter, steady state characteristic