Abstract: The new hydrogen compressor unit is the core equipment in the hydrogenation unit. It has many moving parts, which is prone to failure. This paper briefly introduces the basic situation of the new hydrogen compressor unit of the 1.60Mt/a diesel hydrotreating unit. Aiming at the current secondary load abnormal fault, motor bearing burnout, HydroCOM system failure and other problems occurred during the operation of the unit and combining with previous maintenance experience, the paper found out the causes of the failure and proposed some measures for improvement, which achieved good results. This provides valuable experience for long-cycle operation of reciprocating compressors of the same type.