Abstract: In this paper, the semi-analytical solutions for a particle impacting on simply-supported Timoshenko beam with finite length is obtained by using the method of mode superposition. The characteristics of impact loads varying with respect to time is given, several interesting conclusions about the impact loads are presented, and the exact values of impact loads at initial moment of impact is derived and verified. The propagating characteristics of longitudinal waves and shear waves in a finite-length beam is ...