background: β-Alanine is a precursor of many important pharmaceutical products and food additives, its market demand is continuously increasing nowadays. Whole-cell catalysis relying on the recombinant expression of key β-alanine synthesizing enzymes is an important method to produce β-alanine. Nevertheless, β-alanine synthesizing enzymes found so far have problems including easy inactivation, low expression or poor catalytic activity, and it remains necessary to develop new enzymes. results: Herein, we characterized an L-aspartate-α-decarboxylase, MpADC, from an aphid, Myzus persicae. It showed excellent catalytic activity at pH 6.0-7.5 and 37?°C. With the help of chaperone co-expression and N-terminal engineering guided by AlphaFold2 structure prediction, the expression and catalytic ability of MpADC in Escherichia coli were significantly improved. Using 50?g/L of E. coli cells expressing the MpADC-?39 variant cultured in a 15-L fermenter, 232.36?g/L of β-alanine was synthesized in 13.5?h, with the average β-alanine yield of 17.22?g/L/h, which is best known so far. conclusions: Our research should facilitate the production of β-alanine in an environment-friendly manner.