Abstract: The characteristics of a new kind of liquid natural circulating radiator with fin charged with R11、R113 and R123,respectively,are experimented,and the influences of charging rate on the radiating effect are discussed.The results demonstrate that the radiator owns favorable performances,and it is able to keep the temperature in junction layer of the die steady.For R123,R11 and R113,the performance of R123 is the best and the optimum charge ratio is between 80% and 100%.