A composite seal product with widetemperaturerange and special media resistance was designed based on the basis of temperatureautofrettage principle by using fluororubber as sealing materials and low expansion alloy as structural support.On the condition of given compressibility of rubber,the sealing pressure rate of the composite seal product at ultra low temperature of 20 K was calculated by the finite element analysis method.The result shows that the composite seal product can satisfy with the sealing requirements of new rocket launch system.Sealing simulation experiments verify the leakage of the composite seal product is less than 1×10-5 Pa·m3/s at the temperature range of 20 K to 500 K and in the media of liquid hydrogen,liquid oxygen and coal oil.