Turbo-expander compressor with magnetic bearing is a new type of expander with application of the magnetic field principle to the rotating shaft, replacing the oil lubrication system. It is a technological innovation and breakthrough. In order to enhance the application of turbo-expander compressor with magnetic bearing on natural gas processing, this paper presented its application status in domestic natural gas industry, analyzed its working principles and the characteristics. The rotor is suspended by magnetic force in the limited narrow space of the cavity, so that there is no mechanical friction between the rotor and stator. This bearing operates at high speed, high efficiency, the rotor is not easily damaged. The performance of the whole machine is therefore more stable and reliable. The key technologies of magnetic bearing turbo-expander compressor are the magnetic thrust balancing system and the safe shutdown system. The magnetic thrust balancing system adjusts and ensures the rotor does not deviate from the center space during the high speed movement. The safe shutdown system prevents the rotor from falling and damage when the magnetic field disappears. According to the engineering design and site operating experience, this paper summarized process design essentials and special considerations such as the seal gas system, process gas composition, the software system reliability and bypass J-T valves. The research results could provide technical guidance for selection, maintenance and operation of turbo-expander compressor in natural gas treatment plant.