Cracking gas compressor, propylene compressor and ethylene compressor are the core of ethylene plant, and their ability to maintain high-efficiency operation is extremely important to the safe, stable, long-term and optimal operation of the ethylene plant at full capacity. This article introduces the process of the single test run of steam turbines of the compressors in the megaton ethylene plant at PetroChina Dushanzi Petrochemical Company, including the test run of main and auxiliary oil pumps, condensate pump, emergency shut-off valve and dry gas sealing system, and discusses the reasons and treatment measures against the problems in single test run such as the crank failure, the speed probe detection failure, the high shaft temperature at the drive end of propylene compressor turbine, and the unsuccessful single test run of cracking gas compressor turbine.