Abstract: The spill valve of a high pressure fuel pump fractured during its service. The fracture causes of the spill valve were analyzed by means of dimension design and raw material selection analysis, chemical composition analysis, fracture analysis, metallographic analysis, effective hardening layer depth test, hardness test, galvanized layer thickness test and hole size test. The results show that the failure mode of the spill valve belonged to the delayed hydrogen embrittlement fracture. The carburizing and quenching treatment on the surface of the spill valve resulted in higher hardness and higher hydrogen embrittlement sensitivity. Hydrogen aggregation occurred on the surface of spill valve due to no dehydrogenation treatment during pickling and galvanizing, and hydrogen embrittlement fracture occurred under the combined action of installation stress and hydrogen. Finally, preventive measures were put forward for the fracture causes of the spill valve.