Fluid-injected screw compressor belongs to the oil-free compressor type and has the advantages of both centrifugal compressor and reciprocating compressor, namely high compression ratio, wide capacity adjustment range, stable operation and less parts prone to wear and tear. Optimum fluid injection can absorb the heat generated from compression process, reduce the process fluid discharge temperature, lower the power consumption and effectively improve the operating performance. Fluid-injected screw compressor is suitable to be used as the compressor for process gas containing dust and liquid or gas that polymerise easily. This paper presents the selection of hydrogen compressor, based on the mechanical design and operating principle of fluid-injected screw compressor, and taking into consideration the characteristics of the UOP PDH process. The application of fluid-injected screw compressor is analysed from the aspects of material selection, equipment unit configuration, process system design and reliability in operation. The result shows that, in UOP PDH process, application of the fluid-injected screw compressor is a natural choice as the hydrogen gas contains a certain amount of moisture and condensate will drop out after the compression and cooling process. Furthermore, the use of fluid-injected screw compressor can bring certain advantages in such aspects as plot size, maintenance and capacity adjustment. Fluid-injected screw compressor can adapt to the requriements of the hydrogen compressor in the DOP PDH process, and can improve the compressor’s performance effectively.