Forest　harvesting　is　a　forest　carbon　source.　Accurate　estimation　of　forest　harvesting　biomass　is　helpful　for　accurate　measurement　of　forest　carbon　sinks.　Aiming　at　the　challenging　problem　of　using　single　time-phase　visible　light　UAV　image　to　estimate　the　biomass　of　high-density　forest　harvesting,　a　high-precision　estimation　method　of　forest　harvesting　biomass　was　studied　based　on　multi-temporal　visible　light　UAV　image　before　and　after　logging.　Taking　a　coniferous　forest　in　Fuzhou　City　of　Fujian　Province　Baisha　forest　cutting　small　class　as　the　experimental　zone,　collecting　resolution　better　than　10　cm　long　before　and　after　cutting,　unmanned　aerial　vehicle　(　UAV)　visible　light　image,　the　local　maximum　dynamic　window　method　was　adopted　to　get　high　precision　of　cutting　plants　and　single　tree　height　information,　and　then　based　on　the　UAV　image　after　cutting,　detection　and　extraction　by　the　method　of　YOLO　v5　cut　pile　diameter　of　information,　the　DBH　information　of　the　cut　wood　was　estimated　according　to　the　DBH　-　pile　diameter　model,　and　the　biomass　of　the　cut　wood　was　estimated　by　using　the　binary　biomass　formula　of　tree　height　and　DBH,　which　was　verified　by　the　measured　data.　The　precision　of　tree　number　and　average　tree　obtained　by　dynamic　window　local　maximum　method　was　96.　35%　and　99.　01%,　respectively.　The　overall　accuracy　of　pile　cutting　target　detection　by　YOLO　v5　method　was　77.　05%,　and　the　accuracy　of　average　DBH　estimated　by　pile　cutting　diameter　was　90.　14%　.　Finally,　the　accuracy　of　forest　harvesting　biomass　was　83.　08%　.　The　results　showed　that　this　method　had　great　application　potential.　Using　multitemporal　UAV　visible　light　remote　sensing　before　and　after　harvesting　can　realize　effective　estimation　of　forest　harvesting　biomass,　which　can　help　to　reduce　the　cost　of　manual　investigation,　and　provide　effective　technical　support　for　the　government　and　relevant　departments　to　accurately　measure　carbon　sinks.　©　2023　Chinese　Society　of　Agricultural　Machinery.　All　rights　reserved.