Accurate　and　timely　spatiotemporal　distribution　information　of　soybean　is　vital　for　sustainable　agriculture　development.　However,　it　is　challenging　to　establish　a　phenology-based　automated　crops　mapping　algorithm　at　large　spatial　domains　by　simply　applying　vegetation　index　temporal　profile.　This　study　developed　a　Phenologybased　automatic　Soybean　mapping　algorithm　through　combined　Canopy　water　and　Chlorophyll　variations　(PSCC).　Three　phenology-based　indices　were　designed:　the　ratio　of　change　magnitudes　of　vegetation　index　to　water　stress　index　during　the　late　growth　stage　(T1),　the　mean　concentration　of　chlorophyll　during　the　whole　growth　period　(T2),　and　the　accumulated　variations　of　chlorophyll　before　and　after　heading　date　(T3).　Soybean　was　distinguished　by　lower　T1　and　T3　and　higher　T1　due　to　higher　senescence　water　loss　and　chlorophyll　content.　The　PSCC　method　was　validated　in　Northeast　China　from　2017　to　2021　and　in　four　states　(Missouri,　Illinois,　Indiana,　and　Ohio)　of　the　United　States　(US)　in　2020　using　Sentinel-2　datasets.　Soybean　planting　areas　obtained　by　PSCC　were　consistent　with　the　corresponding　agricultural　statistical　area　(R-2　＞　0.83).　The　soybean　maps　were　evaluated　using　5702　reference　data,　and　the　overall　accuracy　and　kappa　coefficient　were　91.99%　and　0.8338,　respectively.　The　overall　accuracy　for　soybean　mapping　was　improved　by　16.07%　compared　with　using　only　canopy　water　variation.　The　result　showed　that　our　method　could　be　applied　to　large　spatial　domains　and　multi-years　without　retraining.　The　soybean　planting　area　in　Northeast　China　expanded　substantially　25,867　km(2)　(by　89.10%)　during　the　period　2015-2020　and　decreased　slightly　7,535　km(2)　(by　13.73%)　from　2020　to　2021.　Soybean　expansion　occurred　mainly　in　ever-planted　regions.　Northeast　China　contributed　about　60%　to　the　national　soybean　revitalization　goal　in　2020.　This　study　provided　information　on　the　soybean　spatiotemporal　changes　in　Northeast　China,　which　was　significant　for　agricultural　policymakers　to　formulate　soybean　production　plans　to　achieve　national　soybean　revitalization.