In order to adapt to the increasingly complex wireless communication environment and make full use of the scarce spectrum resources, this paper designs and implements an electrically tunable microstrip bandpass filter based on centrosymmetric structure and varactor diodes. The electromagnetic simulation software HFSS is used to conduct simulation experiments. On the split ring resonator structure loaded with branches, an interdigital structure and a spur-shaped coupled feeder are introduced to complete the prototype design of the filter. On the basis of the original, a variable capacitance diode with adjustable capacitance value is added to adjust the low-frequency transmission zero point to realize the reconfiguration of the passband bandwidth, so as to achieve the purpose of flexibly controlling the filtering performance. The actual test shows that the initial relative bandwidth of the filter is 5.1%, the absolute bandwidth is 170 MHz, the absolute bandwidth adjusted by the varactor diode is in the range of 140~200 MHz, that is, 82.4%~117.6%, the center frequency is in the range of 2.70~2.76 GHz, and the transmission zero point tuning range is 2.57~2.63 GHz, the insertion loss in the passband is in the range of 0.9~1.5 dB, and the return loss is in the range of 10~35 dB. The test results are basically consistent with the simulation, and it has certain application prospects in the direction of precious bandwidth control in the S-band.