Abstract: It is the first major step to determine the coagulation time of milk during cheesemaking process. It is closely related to cheese yield and quality. The research is aimed at developing a new and non-destructive method using ultrasound resonance for determining the coagulation time. That is to measure changes in physical properties during milk coagulation process for defining the coagulation time and then the optimal cutting time of coagulum. The study indicates that the ultrasonic attenuation change is closely interrelated to the physical characteristic changes during milk coagulation process. With this method measuring accuracy can be improved obviously.