Gear　modification　can　improve　contact　load　distribution　on　gear　teeth　surface　and　reduce　transmission　error.It　is　an　important　measure　to　reduce　a　transmission　system＇s　vibration　and　noise.To　clarify　the　mapping　relationship　between　gear　modification　parameters　and　transmission　error　has　very　important　theoretical　and　engineering　significances　for　guiding　gear　modification　and　improving　transmission　performance.As　a　gear　transmission　system　has　a　very　complex　nonlinearity,　however,　it　is　difficult　to　derive　an　analytical　expression　for　the　above　mapping　relationship.Here,　taking　a　helical　gear　pair　as　a　study　object,　taking　tooth　profile　modification　and　tooth　direction　one　as　arguments　or　parameters,　the　relation　function　between　gear　modification　and　dynamic　transmission　error　fluctuation　was　fitted　with　the　response　surface　method　and　Kriging　method,　respectively.Then　gear　modification　parameters　were　further　optimized.The　simulation　results　based　on　Romax　were　taken　as　a　benchmark,　accuracies　of　the　two　fitting　methods　were　compared.　The　results　showed　that　Kriging　method　has　a　higher　accuracy　to　fit　the　relation　between　gear　modification　and　dynamic　transmission　error　fluctuation　than　the　response　surface　one　does;　the　tooth　direction　modification　has　a　larger　influence　on　the　dynamic　transmission　error　fluctuation　than　the　tooth　profile　one　does.　©　2018,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.