In recent years, the capacity of ethylene plant has been continuously expanded, and cracking gas compressor unit is developing towards large scale. At the same time, the requirements for the design and performance of compressor unit are higher. Based on the problems in the operation of cracking gas compressor unit of a 200 kt/a ethylene plant, this paper introduces the equipment, facilities and related technologies for the cracking gas compressor and driving steam turbine of the 1200 kt/a ethylene plant of SINOPEC Tianjin Company. The innovative application of a number of advanced technologies has solved some of the key problems in the ethylene plant, providing a strong guarantee for the design and construction of subsequent larger-scale ethylene plants.