In　order　to　reduce　the　vibration　and　noise　of　planetary　gear　train,　a　comprehensive　tooth　modification　strategy　to　minimize　the　dynamic　transmission　error　fluctuation　of　meshing　gear　pairs　is　proposed.　An　analytical　bending-torsion-translation-swing　coupling　dynamic　model　of　a　helical　planetary　gear　train　is　established,　with　which　the　dynamic　transmission　error　of　each　gear　pair　is　solved　by　using　the　Runge-Kutta　method.　Meanwhile,　the　contact　pressure　on　the　engaging　tooth　surface　is　numerically　simulated　by　using　the　software　of　Romax.　The　theoretical　calculations　and　numerical　simulations　indicate　that　without　tooth　modifications,　there　exist　noticeable　fluctuation　of　dynamic　transmission　errors　and　uneven　load　distributions　of　the　tooth　surfaces,　leading　to　meshing　impacts　at　engage-in　and　engage-out　positions.　Accordingly,　a　comprehensive　modification　strategy　of　crowned　modification　in　the　lead　direction　and　involute　modification　in　the　profile　direction　is　proposed.　Based　on　the　meshing　theory,　the　component　of　the　modification　function　along　the　line　of　action　is　derived,　which　is　further　incorporated　into　the　aforementioned　dynamic　model　to　recalculate　the　dynamic　transmission　errors　of　meshing　gear　pairs.　A　quadratic　polynomial　function　with　crossed　terms　is　derived　with　the　response　surface　method　to　describe　the　quantitative　relationship　between　the　amounts　of　tooth　modification　and　the　dynamic　transmission　error　fluctuation.　By　minimizing　the　quadratic　polynomial　function,　the　optimal　tooth　modification　parameters　of　an　individual　gear　pair　can　be　determined.　The　optimal　modification　parameters　of　the　internal　and　the　external　gear　pairs　are　further　set　as　the　mean　value　of　the　modification　design　variables　to　fit　the　response　surface　function　of　the　planetary　gear　system.　The　optimized　modification　parameters　for　the　helical　planetary　gearings　are　obtained　with　the　minimum　fluctuation　of　transmission　errors.　Finally,　the　dynamic　characteristics　of　a　helical　planetary　gear　train　with　and　without　modifications　are　compared.　The　comparison　results　show　that　the　proposed　tooth　modification　strategy　can　effectively　improve　the　contact　status　of　engaging　surfaces　and　reduce　the　dynamic　transmission　error　fluctuations　of　each　gear　pair　within　4　μm.　©　2019,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.