In　order　to　explore　the　critical　factors　that　influence　the　reliability　of　CNC　grinding　machine,　and　find　the　measures　to　improve　the　reliability　and　performance　of　CNC　grinding　machine,　the　reliability　mathematical　model　of　CNC　grinding　machine　is　analyzed　and　formulated.　Firstly,　the　dependence　of　the　failure　models　is　tested　based　on　the　field　failure　data.　Secondly,　the　probability　density　function　and　cumulative　distribution　function　for　the　performance　of　CNC　grinding　machine　are　plotted.　Finally,　the　mean　time　between　failures　(MTBF)　as　the　main　reliability　index　of　CNC　grinding　machine　is　evaluated　using　the　proposed　model　and　functions.　Reliability　evaluation　for　CNC　grinding　machine　can　provide　references　to　learn　the　reliability　level　and　re-design　for　the　CNC　grinding　machine.