Screw compressor is composed of a pair of parallel and engaged Yin and Yang screws, which is the most widely used in rotary compressor, divided into two kinds: single screw and double screw. The shaft seal structure is used in the screw compressor to maintain the sealing structure. And the general shaft seal structure can not adapt to the axial movement of the shaft rod, and the sliding friction inside the shaft seal structure is large, the structure is easy to be damaged, not convenient for long-term use.