Abstract: Memristor is used as an RF switch in this paper. Based on a dual-mode resonator and an improved shortcircuited stepped-impedance resonator, a tri-band bandpass filter is designed. The position of memristor bias circuit is optimized. The memristor′s impedance is nonvolatile, and this characteristic is used to realize the switchable function of filter passband. When the filter is working, memristor is in the memory state of power-off, which will improve intermodulation performance of filter. This filter has four switchable modes: tri-band, dual-band, single-band and full-stopband working mode. The measured results show that the insertion loss of tri-band working mode is -1. 38 dB@ 1. 75 GHz, -0. 94 dB@ 3. 10 GHz and -3. 13 dB@ 3. 70 GHz; the insertion loss of dual-band working mode is -1. 67 dB@ 1. 75 GHz and -3. 10 dB@ 3. 70 GHz; the insertion loss of single-band working mode is -1. 35 dB@ 3. 10 GHz; the rejection of full-stopband working mode is higher than 24. 85 dB. The alternative test method is used in this paper,and measured results are consistent with simulated results.