The invention discloses a boronic acid having a structure shown in a formula I and an ester compound thereof. In the formula I, R1 and R2 may be substituted or non-substituted C1 to C10 alkyl, C3 to C6 cycloalkyl or hetercycloalkyl, benzyl, menaphthyl or indolemethyl respectively and independently, wherein substituents may be C1 to C4 alkyl, cyan, hydroxyl, sulfhydryl, amino and halo; Z1 and Z2 may be hydroxyl, C1 to C10 alkyl, C1 to C10 alkoxy or aryloxy respectively and independently, or B, Z1 and Z2 form a heterocyclic group containing N, S or O together; and Pg represents substituted or non-substituted bicycloacyl or trocycloacyl group having at least one unsaturated ring, wherein substituents may be C1 to C4 alkyl, C1 to C4 alkoxy, halo or C1 to C4 halogenated alkyl. The invention also discloses a preparation method of the boronic acid and the ester compound thereof and use of the boronic acid and the ester compound thereof in the preparation of antineoplastic medicaments.