Tyrosine decarboxylase (TDC) is an enzyme that catalyzes the decarboxylation of L-tyrosine to produce tyramine and CO2. In this study, the vector pET-28a was used to recombinant expressed the tdc gene from Lactobacillus brevis in Escherichia coli BL21 (DE3). Several influencing factors of the enzyme reaction, such as pH, temperature, coenzyme, concentration of substrate, were all investigated. The results indicated that the recombinant tyrosine decarboxylase was successfully expressed and the reaction was optimal at pH 5.5 and 40℃, 0.02 g/mL cells, 0.2 M acetic acid buffer solution (pH 5.5), 0.2mM 5-pyridoxal phosphate and 0.18 g/mL L-tyrosine. After 7 hours, the mole conversion rate of L-tyrosine was up to 99%. TDC’s enzyme activity is 29.2 U/g. The Km and Vmax values of TDC were 0.71mM and 9.31mol/L?min?g.