The　influential　factors　of　geogrid　tension　such　as　pile　spacing,　subgrade　height,　soil　modulus　of　pile　tip　and　geosynthetic　reinforcement　layer　modulus　under　dynamic　train　load　are　studied　based　on　the　dynamic　finite　element　model　of　pile　net　subgrage　structure.　The　results　show　that　the　longitudinal　geogrid　tension　increases　with　the　increase　of　pile　spacing.　Besides,　pile　spacing　has　little　effect　on　the　geogrid　tension　in　soil　between　piles　when　it　reaches　2　m　or　more,　but　it　has　great　effect　on　the　geogrid　tension　in　the　pile-top　and　at　the　edge.　The　value　of　geogrids　tension　is　proportional　to　that　of　subgrade　height.　The　value　of　geogrids　tension　decreases　with　the　increase　of　soil　modulus　of　pile　tip,　and　the　effect　of　the　latter　could　be　neglected　when　it　reaches　100　MPa,　which　is　little　affected　by　the　change　of　geosynthetic　reinforcement　layer　modulus.　The　geogrid　tension　increment　increases　with　the　increase　of　subgrade　height,　but　decreases　with　the　increase　of　soil　modulus　of　pile　tip.　For　the　geogrids　distributed　from　the　center　to　the　edge　of　subgrade　section,　the　effect　of　the　above　four　influential　factors　to　the　geogrid　tension　have　the　same　variation　regularities,　however,　such　effect　become　weaker　at　the　road　shoulder　compared　to　the　subgrade　center,　and　the　weakest　at　the　slope　toe.　©　2017,　Editorial　Department　of　Journal　of　Beijing　Jiaotong　University.　All　right　reserved.