A　new　notion　is　proposed　that　all　of　the　real　flanks　of　one　or　a　sequence　of　manufactured　gears,　as　the　results　of　a　specific　manufacture　process　with　deviations　from　the　identical　theoretical　flank,　can　be　considered　as　a　stochastic　process.　Based　on　statistical　analysis　of　the　stochastic　process,　a　new　evaluation　system　of　gear　accuracy　and　the　definitions　of　a　set　of　statistics　are　proposed.　This　paper　establishes　a　model　to　represent　the　3D　errors　of　gear　flanks.　To　prove　the　validity　of　the　new　statistical　analysis　based　evaluation　method,　simulation　experiments　have　been　carried　out.