Abstract: This paper describes the operation characteristics of variable high-speed motor and variable speed planetary gear motor as well as the environmental protection type gas compressors, discusses the operation properties of the 3 variable speed motors. A comparison between MOPICO and IEMDC compressors is made and the development envisagement on the environmental protection type coaxal gas compressors is provided, and the profits and significance to study and develop this kind of compressor is emphasized.