The molecular weight distribution of the ultrasonic-degraded gelatin was determined with the gel permeation chromatography. It showed that the higher molecular weight components of gelatin was reduced with the time of ultrasonic irradiation. The relationships between molecular weight distribution and viscosity or jelly-strength of ultrasonic-degraded gelatin were studied. It seems that higher molecular weight components are responsible for the viscosity. Jelly strength seems to have correlation with the sum of α and β components minus lower molecular weight components.