The　dynamic　finite　element　model　of　low　subgrade　with　pile-net　structure　was　built　by　using　ABAQUS　software.　The　reliability　of　the　model　was　verified　by　the　comparison　of　calculated　and　measured　results.　The　distribution　of　dynamic　stress,　the　vibration　characteristics　of　pile-soil　stress　ratio　and　the　height　of　equal　settlement　plane　under　train　load　were　analyzed.　Analysis　result　indicates　that　the　maximum　differences　of　calculated　and　measured　values　for　dynamic　stress　and　dynamic　displacement　at　different　depths　of　subgrade　are　0.56　kPa　and　7　μm　respectively,　the　transmission　trends　of　average　dynamic　stress　and　dynamic　displacement　of　calculated　result　are　similar　to　the　measured　result　along　the　subgrade　depth,　so　the　proposed　dynamic　finite　element　model　is　reliable.　There　exists　soil　aching　effect　in　subgrade　under　dynamic　load,　and　the　height　of　soil　arching　effect　is　about　1.6　m　that　is　approximately　the　same　with　the　value　under　static　load.　The　stress　variation　ratio　under　dynamic　load　in　subgrade　surface　is　larger　than　the　value　in　subgrade　base,　and　the　stress　variation　rate　in　subgrade　base　is　extremely　diminutive.　The　distribution　of　dynamic　stress　in　subgrade　under　dynamic　load　is　effected　by　soil　arching　effect,　and　the　dynamic　stress　is　partly　transferred　from　soil　among　piles　to　pile　top,　and　the　phenomenon　is　most　obvious　in　the　cushion　of　subgrade.　After　dynamic　load,　in　the　center　of　subgrade,　the　pile-soil　stress　ratio　of　pile　top　to　soil　between　two　piles　decreases,　and　the　ratio　among　four　piles　increases.　The　pile-soil　stress　ratio　between　two　piles　is　always　larger　than　the　value　among　four　piles.　The　height　of　equal　settlement　plane　of　vertical　section　with　the　distance　of　1　m　to　the　center　of　subgrade　is　about　1.55　m.　The　height　of　equal　settlement　plane　in　vertical　section　with　piles　is　larger　than　the　value　without　piles.　From　subgrade　center　to　subgrade　shoulder,　the　height　of　equal　settlement　plane　in　the　same　vertical　section　decreases　gradually.　After　dynamic　loading,　the　height　of　equal　settlement　plane　in　the　center　of　subgrade　increases.　©　2015,　Editorial　Department　of　Journal　of　Traffic　and　Transportation　Engineering.　All　right　reserved.