Aiming　at　the　limitation　by　the　high　cost　of　test　and　length　cycle　process　of　the　CNC　grinding　machine　reliability　evaluation,　this　article　adopted　small　sample　technology　which　needs　less　data　while　getting　higher　evaluation　accuracy,　by　using　the　theory　of　Bayes　theorem　and　failure　rate　as　of　the　random　variables,　the　experiment　data　of　tracking　CNC　grinding　machine　for　a　year　is　analyzed.　Results　indicate　that　results　acquired　by　this　mean　are　consistent　with　the　actual;　meanwhile,　it　shortens　test　cycle　and　reduces　cost,　which　is　a　very　effective　way　to　analysis　CNC　grinding　machine.　Therefore,　it＇s　very　essential　that　the　small　sample　technology　research　is　applied　in　the　CNC　grinding　machine　evaluation.　©　(2014)　Trans　Tech　Publications,　Switzerland.