The ultra-wide-band filter serves as a key unit in an ultra-wide-band communication system and determines the overall performance of the system. The invention relates a microstrip ultra-wide-band band-pass filter based on a novel multi-branch multi-mode resonator. The filter is characterized in that two ends of an intermediate short-circuit transmission line node 33 are connected with two ends of a transmission line node 32 to form a closed loop, wherein the short circuit of the intermediate short-circuit transmission line node 33 is realized by a metalized through hole 34. An open-circuit transmission line node 31, an open-circuit transmission line node 35, an open-circuit transmission line node 36, an open-circuit transmission line node 37, an open-circuit transmission line node 38, and an open-circuit transmission line node 39 are respectively connected to the transmission line node 32. In addition, the filter performances are improved by connecting matching branches including a short-circuit transmission line node 12 and an open-circuit transmission line node 14 at an input port and connecting matching branches containing a short-circuit transmission line node 22 and an open-circuit transmission line node 24 at an output port, wherein the short circuit of the short-circuit transmission line node 12 is realized by a metalized through hole 13 and the short circuit of the short-circuit transmission line node 22 is realized by a metalized through hole 23. Researches show that the provided microstrip ultra-wide-band band-pass filter has advantages of high performance and miniaturization and the like.