This paper introduces the high exhaust pressure in the driving turbine for propylene refrigeration compressor in the 220 kt/a ethylene plant of a petrochemical company. Through technical research, design optimization and the implementation of technical measures, the working efficiency of the turbine is further improved while eliminating the bottleneck of high exhaust pressure, thus achieving the goal of energy saving and consumption reduction and eliminating the operational hazards in the plant. The operational efficiency of the plant is improved and the cost is reduced through minor modifications in local areas.