Abstract: The frosting rate of the evaporator interface is an important parameter for designing the refrigerator system.In this paper,we described a novel technique of laser diffraction measurement technique to visually and fast determine the frosting rate.There was a space between the frosted surface and the reference surface.When a light went through the space,the diffraction fringes were performed.Then the frosted area expended,the space changed more narrow,and the diffraction fringes moved.With the variation of the location of the diffraction fringes,the frost rate can be precisely determined.