Tyramine has been paid more attention in recent years as a significant metabolite of tyrosine and catecholamine drug and an intermediate of medicinal material and some drugs. In this study, an effective, green, and three-step biocatalytic synthesis method for production of tyramine starting from serine in keratin acid hydrolysis wastewater was developed and investigated. Serine deaminase from Escherichia coli was first combined with tyrosine phenol-lyase from Citrobacter koseri, to convert l-serine to l-tyrosine. l-Tyrosine can then be decarboxylated to tyramine by tyrosine decarboxylase from Lactobacillus brevis. All these enzymes originated from recombinant whole cells. Serine deaminase and tyrosine phenol-lyase could efficiently convert l-serine in wastewater to l-tyrosine at pH 8.0, 37 A degrees C, and Triton X-100 of 0.04 % when tyrosine phenol-lyase and its corresponding substrates were sequentially added. Tyrosine conversion rate reached 98 % by l-tyrosine decarboxylase. In scale-up study, the conversion yield of l-serine in wastewater to tyrosine was up to 89 %. l-Tyrosine was decarboxylated to tyramine with a high yield 94 %. Tyramine hydrochloride was obtained with a total yield 84 %. This study has provided an efficient way of recycling keratin acid hydrolysis wastewater to produce tyramine.