In this paper, an ultra-wideband (UWB) single-ridge waveguide band-pass filter using an efficient and rapid design procedure is proposed. This passive device is constructed from the filter section and the transition sections. The simulation results show that the return loss of the filter section is better than 19 dB in 3.05 ∼ 10.9 GHz and the S11 of transition is closing to −17dB. The insertion loss of the whole structure is −0.11 dB, and the return loss is below −16 dB in the pass band from 3.1 to 10.6 GHz. Besides, the design method in the whole design procedure drastically reduces the CPU time for optimization.