In order to study the low temperature sealing mechanism of rubber sealing materials for liquid rocket,the low temperature performances of five commonly used rubber sealing materials for liquid rocket engines were characterized by various low temperature characteristic temperature testing methods of rubber materials.The sealing ability of various rubber materials at low temperatures under different compression ratios,working temperatures,and pressure differentials was studied by simulation analysis and experimental verification.The results show that the sealing ability of rubber under low compression in low-temperature environment is higher than that under high compression.In low-temperature environments,due to the sharp increase in low-temperature shrinkage and elastic modulus of rubber,it is difficult to cause the deformation of rubber material to form a seal under low pressure difference,and the pressure difference must be increased to produce enough contact pressure on the sealing surface to form a seal.Therefore,the low temperature sealing ability of rubber material is related to the low-temperature shrinkage performance,the elastic modulus of the material,and the pressure difference,and when the working temperature exceeds the critical temperature of rubber at low temperature,the sealing ability of the O-ring is weak and leakage is prone to occur.