Evaluating　the　shape　and　size　of　the　fracture　process　zone　near　mode　II　and　mode　III　dynamic　crack　tip　is　still　a　problem　unsolved　at　present.　An　approximate　method　for　evaluating　the　shape　and　size　of　FPZ　is　proposed　and　the　feasibility　of　the　method　is　demonstrated　through　a　comparison　with　the　results　calculated　based　on　the　known　stress　fields.　The　shape　and　size　of　the　FPZ　near　the　dynamic　crack　tip　are　determined　based　on　the　new　method,　which　depend　on　the　crack　propagation　velocity.　The　results　show　that　the　FPZ　at　mode　II　and　mode　III　dynamic　crack　tip　distributes　symmetrically　with　respect　to　the　crack　plane　and　increases　with　the　crack　propagation　velocity.　FPZ　changes　more　rapidly　when　the　Rayleigh　wave　velocity　is　approached.　The　size　of　FPZ　calculated　by　Tresca　criterion　is　larger　than　that　calculated　by　Von　Mises　criterion.　©　2020,　Engineering　Mechanics　Press.　All　right　reserved.