Abstract: The new helium refrigerator of space environment simulator supplies the cold environment for in cryo pump. Sucessful development of helium refrigerator represens the superiority of design. The advanced helium screw compressor, turbine dismantled vessel with integral functions and in purfier system with particular configuration are designed. This system is of high automatization We have conducted the thermal test of "shenzhou" experimental spacecraft by using this system In the future it will creat the guarantee condition for all kinds of spacecraft the tests of which need a 20K cold background.