The invention discloses a 4-hydroxyphenylacetic acid 3-
monooxygenase mutant and application thereof, the 4-hydroxyphenylacetic acid 3-
monooxygenase mutant comprises seven single mutants, the seven single mutants are respectively Q212T, Q212A, V213P, V213A, Y301R, N460M and N460A, and the
gene sequence is shown as SEQ ID NO.1-7. The invention further discloses a preparation method of the 4-hydroxyphenylacetic acid 3-
monooxygenase mutant. According to the invention, a high-activity 4-hydroxyphenylacetic acid 3-monooxygenase mutant EcHpaB is constructed, after the mutant and a
reductase component EcHpaC are co-expressed, the co-expressed mutant and
reductase component EcHpaC and CsF3H are introduced into an
escherichia coli
chassis at the same time, the mutant and the
reductase component EcHpaC can be used for preparing dihydroquercetin, the 3 '-
hydroxylation reaction efficiency is remarkably improved, and efficient production of dihydroquercetin is realized; the method does not need to depend on
heterologous P450
enzyme, has the advantages of being simple in
heredity, convenient and fast to operate, low in
fermentation cost and the like, and provides a new synthesis thought for efficient production of dihydroquercetin.