Aiming　at　cases　of　influence　of　contact　ratio　being　not　considered　in　traditional　tooth　modification　methods,　and　noise　and　vibration　reduction　effect　being　not　significant　only　considering　reduction　of　amplitude　of　loaded　transmission　error　(ALTE)　for　high　speed　gears,　a　new　tooth　surface　modification　method　considering　contact　ratio　or　overlap　ratio,　and　an　approach　for　calculating　mesh-in　impact　force　based　on　the　tooth　contact　analysis　(TCA)　and　the　loaded　tooth　contact　analysis　(LTCA)　were　proposed.　Ultimately,　based　on　the　intelligent　optimization　algorithm　and　the　proposed　tooth　surface　modification　method,　an　optimization　model　was　established　to　minimize　ALTE　and　mesh-in　impact　force,　and　the　optimal　tooth　surface　modification　values　were　determined　through　the　multi-objective　optimization.　The　actual　example　calculation　results　showed　that　compared　with　the　traditional　tooth　surface　modification,　the　proposed　new　method　can　be　used　to　effectively　reduce　fluctuation　of　loaded　transmission　error　and　mesh-in　impact　force.　©　2019,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.