Non-obstructive particle damping is a composite damping technology based on traditional particle damping and impact damping. Being Compared with viscous elastic damping structure, advantage of NOPD is damping characteristic of system improved greatly on the basis of specific whole designing structure and whole mass. The technology has good general vibration-reduced outcome. Beam structure is a common structural element form in engineering application. Because of vibration or instability of beam under external excitation, in this paper, free beam is regarded as an object, and many factors affecting damping characteristic of NOPD are studied, which supplies referring results for engineering application of NOPD.