A macrocyclic derivative of pyrazol[3,4-d]pyrimidin-3-one as represented by formula (I) and/or a pharmaceutically acceptable salt thereof, a composition comprising the compound as represented by formula (I) and/or a pharmaceutically acceptable salt thereof, a preparation method therefor, use thereof as a Wee1 inhibitor and use thereof as a sensitizer in chemotherapy or a radiotherapy of cancers. The macrocyclic derivative of pyrazol[3,4-d]pyrimidin-3-one can effectively inhibit Wee1 and relating signaling pathways, having good therapeutic and relieving effects on cancers.