A novel method for the realization of high selectivity millimeter wave band pass filters is presented. A small perturbing notch was etched at sidewall of a dual-mode circular cavity to improve cross coupling between two orthogonal modes. By properly changing the perturbing angle, the bandwidth is expanded and location of the transmission zero can be easily adjusted to significantly enhance the filter selectivity. The V-band filters have been designed, fabricated and measured. The experiment results showed an excellent agreement with simulation results. Unlike conventional filters, the proposed prototypes do not need any additional mechanical tuning element. It has merits of simple design process, high selectivity, compact size and quasi-planar structure.