Abstract: The gelatin was irradiated respectively in the range of 0.32 kGy by dose rates of 60 Gy/min ⁶⁰Co, 480 Gy/min ⁶⁰Co and 12 000 Gy/min accelerator, and the relationships of the radical character and gelatin property with dose rate were investigated through electron spin resonance (ESR) and gelatin permeation chromatogram. The results show that there is weak ESR signal from unirradiated gelatin, but irradiated one presents typical double peak. The order of ESR signal intensity of gelatin with the same absorbed dosage from high to low is 60 Gy/min ⁶⁰Co, 480 Gy/min ⁶⁰Co and 12 000 Gy/min accelerator. The linear relationship between ESR signal intensity from ⁶⁰Co irradiated gelatin and absorbed dose is y=26.983x²+1 641.8x-205.69. The intrinsic viscosity, average relative molecular weight, gelatin strength and breaking elongation of irradiated gelatin from high to low are 480 Gy/min ⁶⁰Co, 12 000 Gy/min accelerator and 60 Gy/min ⁶⁰Co. The protection mechanism of high dose rate radiation on gelatin degradation is that the production of effective long life free radicals reduces.