In　view　of　the　lack　of　relevant　research　on　CNC　grinders　in　the　field　of　reliability　research　of　CNC　machine　tools　at　present,　This　research　collected　reliability　data　based　on　19　MSK　series　grinder　machine　tools　of　a　machine　tool　factory.,　found　out　the　crucial　subsystem　which　is　the　most　important　component　to　the　whole,　and　analyzed　the　reliability　of　the　subsystem　adopting　FTA　(Fault　Tree　Analysis)　.　Statistical　researched　on　438　reliability　data　collected,　combining　with　the　actual　production　situation,　the　results　shows　that　cooling　system　is　the　key　to　the　reliability　of　the　whole　grinder　machine　tool.　The　29　minimum　cut　sets　obtained　by　FTA　can　be　adjusted　to　improve　the　reliability　of　the　cooling　system,　what　is　more,　the　reliability　of　grinder　machine　tool　would　be　improved　as　well.　©　Published　under　licence　by　IOP　Publishing　Ltd.