The present invention relates to the preparation field of azoxystrobin, and discloses a preparation method for a compound represented by formula (I). The method comprises the following steps: (1) a compound represented by formula (II) is hydrolyzed in a solvent under acidic conditions to obtain a compound represented by formula (III); and (2) the compound represented by formula (III) is reacted with a base and a methylating agent to obtain the compound represented by formula (I); in the formula, R3 is hydrogen or C1-C4 alkyl, and R4 is C1-C4 alkyl. The process for preparing azoxystrobin of the present invention not only successfully replaces trimethyl orthoformate and reduces the raw material cost, but also has high total reaction yield, and is suitable for industrial large-scale production. Experiments have proven that the yield of the prepared azoxystrobin can reach 95%.