A　series　of　pyrazolo[3,4-d]pyrimidin-4-one　scaffold　were　designed　and　synthesized　as　novel　CDK2　inhibitors.　By　analyzing　the　common　motifs　of　various　known　inhibitors,　the　designed　compounds　1　were　virtually　screen　for　their　inhibitory　activity　by　docking　into　the　active　pocket　of　CDK2.　The　influence　of　different　substitutes　on　the　docking　results　was　investigated.　A　total　of　15　pyrazolo[3,4-d]pyrimidin-4-ones　1　were　synthesized　by　Paal-Knorr　reaction,　pyrimidine　ring　closure,　bromination,　Suzuki　coupling　reaction,　amide　formation　and　Knoevenagel　condensation.　The　Cell　Counting　Kit-8　(CCK-8)　was　used　to　evaluate　the　inhibitory　activity　of　pyrazolo[3,4-d]pyrimidin-4-ones　1　in　the　breast　cancer　cell　line　MCF-7　in　vitro　using　Etoposide　as　a　reference　control　substance.　The　screening　results　demonstrated　that　the　designed　compounds　have　significant　antiproliferative　activity,　and　compounds　1e　and　1j　were　the　most　active　compounds　with　IC50　values　of　10.79　mu　M　and　10.88　mu　M,　respectively,　being　better　than　that　of　Etoposide　(IC50　=　18.75　mu　M).　The　enzyme　inhibition　assay　was　carried　out　against　CDK2,　the　results　indicated　that　the　compounds　1e　and　1j　significantly　inhibited　CDK2　with　IC50　values　of　1.71　mu　M　and　1.60　mu　M.