Disclosed are a pyrazolone-pyrimidine compound, a preparation method therefor and an application thereof. The present invention provides a pyrazolone-pyrimidine compound as represented by formula (I), and an enantiomer, a diastereomer, a tautomer, a crystalline form, a pharmaceutically-acceptable salt, a solvate, a metabolite, or a prodrug thereof. The compound has a high inhibiting activity for WEE1 kinase.