Abstract: A compound represented by formula I and a racemate, a stereoisomer, a tautomer, an isotopic marker, nitrogen oxide, a solvate, a polymorph, a metabolite, an ester, a pharmaceutically acceptable salt or a prodrug thereof, a pharmaceutical composition comprising same, a preparation method therefor, and a pharmaceutical use thereof are described. The compound has the activity of inhibiting USP28 and/or USP25. The structure of the formula I is as follows.