As we know, strong mechanical vibration exerts baneful influence upon our health. The load rate K is an important Parameter in describing the mechanical vibration on human body. It is also used as a quantitative control criterion. This Paper summarizes the researches concerning the loading of mechanical vibration on human body and control criteria used in various countries. It presents a new method of calculating the load rate K, by means of mutifrequencies in the frequency spectrum of vibration instead of the currently-used single frequency, so that the load rate K will be resonable.