The invention relates to a preparation method of L-erythro biopterin compound. Among them, the L-erythro biopterin compound is of a structure as shown in formula (I), and the L-erythro biopterin compound represented by formula (I) is mainly obtained by a dihydroxylation reaction of the compound with a structure as shown in formula (II) or formula (III);
The preparation method of L-erythro biopterin compound is of high production efficiency, low cost, is environment-friendly, and suitable for industrial production.