A novel three-pole microstrip bandpass filter using mixed capacitor-loaded asymmetric quasi-combline and combline resonators is proposed. The equivalent circuit of the design is demonstrated and analyzed based on odd- and even-mode method in detail. According to the overall equivalent circuit, two transmission zeros can be introduced at both sides of the passband，which improves the selectivity significantly. The measured central frequency in the passband of the fabricated filter is 1.83 GHz，and the relative bandwidth is 9%. The insertion loss is only 1.45 dB with its return loss better than 14 dB. The measured results show good agreement with the simulated ones.