In　the　process　of　development　in　the　oilfield,　scale　has　been　produced.　Thus　laboratory-scale　deposition　tests　have　been　used　to　understand　scale　deposition　mechanism.　The　process,　mechanism　and　the　main　type　of　the　scale　in　Asp　flooding　well　of　the　forth　plant　of　the　Daqing　oilfield　were　analyzed.　To　investigate　the　concentration　change　of　the　ions　in　the　formation　water　with　the　injection　of　the　Asp　complex　liquid　and　the　scaling　mechanism　in　the　process　of　Asp　flooding　the　core　dissolution　test　was　carried.　Some　of　the　scale　samples　were　characterized　by　scanning　electron　microscope　(SEM),　and　the　results　of　the　element　analysis　were　investigated.