Abstract: Polymer PTFE, PCTFE and PEEK were used as the valve seat soft sealing materials of vale seat for cryogenic control valve and the relationship between leakage rate and sealing pressure was analyzed at room temperature (300 K). Based on those results, the tests of valve seat's leakage rate and stability in different inlet pressure were carried out. Tests analysis results showed that the cryogenic valve with PCTFE as the valve seat soft material had excellent sealing performance and higher pressure stability in different inlet pressure.