A novel tri-band bandpass filter (BPF) based on two multi-mode resonators is presented. The even–odd-mode analysis method is adopted to calculate the resonant modes of the resonators. The formation of each passband is analysed in detail. Furthermore, introduction of seven transmission zeros adjacent to the passbands in a narrow frequency range improves the selectivity of the system, resulting in sharp skirts. Due to the small multi-mode resonator and tight coupling structure, the overall size of the proposed filter is really compact (0.19 λ0 × 0.19 λ0), where λ0 is the wavelength of the centre frequency of the first passband in the substrate. Finally, a prototype to demonstrate the performance of the proposed tri-band filter is designed and fabricated. The locations of the passbands are chosen to be 2.29, 2.81 and 3.42. The measurement shows good agreement with the simulation. The proposed tri-band BPF can be applied to F-band multi-mode RF front end systems.