The invention relates to a preparation method of a pyran derivative hydrochloride hydrate and an intermediate of the hydrate, and concretely relates to a preparation method of a compound represented by formula (XII) and an intermediate of the compound. The intermediate comprises a compound represented by formula (I), and the compound represented by formula (I) is prepared through reacting a compound of formula (III) with a methylation reagent to obtain a compound of formula (II-A) and reacting the compound of formula (II-A) with HX to generate the compound represented by formula (I). The preparation method has the advantages of mild reaction conditions, simplicity in operation, high reaction yield, high product purity, convenience in post-treatment, and suitableness for industrial production.