This invention discloses a sort of bi-bar concussion tunableness vibration excitor, which includes strike-head, dowel bar, falling weight, spring, gun barrel, and seat. One end of is fastened to the gun-seat. Dowel bar, falling weight and spring install in the gun barrel in turn. The spring is in the bottom of the gun barrel. The strike-head is fastened to dowel bar. There is more than one hole on the dowel bar. Dowel male pin hole on the dowel bar matched to the location hole. The dowel male pin is fastened to gun barrel. This invention has simplicity construction, convenience operation, high precision, which is an ideal testing apparatus for dynamic behavior analysis, modal analysis, non-destructive testing.