In　this　paper,　theoretical　and　experimental　researches　were　done　to　find　the　repeated　cracking　reason　of　stuffing　box　in　a　super　hyper　pressure　compressor.　The　mathematical　expression　of　the　assembly　pressure　was　deduced　in　interference　fit.　From　macro　and　micro　perspectives,　residual　stresses　were　measured　by　X-ray　diffraction　in　typical　position　of　stuffing　box　when　the　packing　box　in　combination　and　separation　states.　Besides,　metallography　and　fracture　examinations　were　carried　out.　The　results　showed　that　the　real　magnitude　of　shrink　range　of　the　failed　stuffing　box　was　only　account　for　12%　of　the　designed　size　requirements,　however,　under　this　working　condition　this　stress　was　not　sufficient　to　cause　cracking;　Unqualified　smelting　process　and　tensile　stress　concentration　in　tank　caused　micro　crack,　which　finally　results　in　fracture　of　the　stuffing　box　under　fatigue　mode.