Abstract: To satisfy the demand of high selectivity and more compact in filter,rectangular cavity and inductive post are used to design a dual-mode resonance cavity which achieve the response of pseudo-elliptic filter. A fourth-order bandpass filter is constructed by cascading two dual-mode resonance cavities.The results show that inductive post perturbing electrical fields of dual-mode and the lower order mode can resonate. Dual-mode resonance realizing two poles in passband and a transmission zero（ TZ） out of band. The TZ controlled by the offset distance between the input waveguide and output one. While this offset increased from 2 mm to 4 mm,the position of TZ shift up about 1.04% and the amplitude increased about 45.38%. The TZ placed in the upper stopband when the resonant frequency of even mode is lower than odd mode. A second-order TZ is built by cascading cavities and the restrain level of stopband can improved. The designed filter compact and have good performance,it can be used in higher order by cascading more resonance cavities.