Propylene refrigeration compressor is one of the critical equipment in ethylene plant and is driven by steam turbine. To solve the problem of sudden change in the axial position of propylene refrigeration compressor, this article uses the condition monitoring software to determine through the analysis of gap voltage trend and condition monitoring map that the root cause of the sudden change is the malfunction of fire sprinkler system of the compressor, which led to the deformation of bearing housing. The influence of the design defects of the fire sprinkler system on the stable operation of compressor unit is eliminated by upgrading the deluge valve structure and optimizing the spray nozzle layout.