Abstract: Applying the theory put forward by reference 3,this paper studies the problem of radiation on a vibrating steel plate,and discusses the radiation mechanism and the radiating acoustical energy.Between the point radiation resistance efficiency and the point radiation reactance efficiency exists the chromatic dispersion relation which is one to one.The chromatic dispersion relation fits not only smooth curves,but also the dispersed sharp-pointed waves.While vibrating surface radiates acoustical energy into field,the vibrating surface absorbs some acoustical energy from the field.