通过化学成分分析、断口分析、力学性能测试和金相检验等方法分析了DW-34.7/(11.5-53)X型压缩机活塞与十字头断裂失效的原因。结果表明:活塞和十字头失效的主要原因是材料组织不合格,使材料力学性能不能满足安全使用要求。同时，活塞螺母没有锁紧装置，在交变载荷下使活塞受力恶化，活塞最先失效，加上十字头存在高周疲劳裂纹，从而导致整个失效事故发生。并根据分析的结果提出了预防措施。

The fracture failure reason of piston and crosshead of DW-34.7/(11.5-53)X type compressor was analyzed by means of chemical composition analysis, fracture analysis, mechanical properties testing and metallographic examination. The results showed that the main failure reason of compressor piston and crosshead was the unqualified microstructure.It made material mechanical properties can not satisfy the safe usage requests. At the same time, by reason of piston nut had not locking device, under alternating load, piston and piston rod had occured relative movement, resulting in the deterioration of the piston force, pistons first occurred failure accident，and high cycle fatigue cracks existed in crosshead, resulting in the next accident finally. At last, according to analytic results, the prevention measures were put forward.