To achieve the purpose of efficient, low cost catalytic synthesis of L- tryptophan, tryptophanase from Enterobacter aerogenes was recombinant expressed in Escherichia coli BL21(DE3) using plasmid pET30a as vector. The enzymatic properties of the recombinant tryptophanase were studied, and several influencing factors of the enzyme reaction, such as temperature, initial pH, mass concentration of pyruvic acid, n (indole) / n (pyruvic acid) were investigated with pyruvic acid, indole and ammonium as substrates. Then, pyruvate fermentation broth, indole and ammonium were transformed to L-tryptophan by the recombinant tryptophanase. The results indicated that the recombinant tryptophanase was successfully expressed, and the optimal conditions for the enzymatic conversion were 35 oC, initial pH=9.0, c (pyruvic acid) =0.17 mol/L, and n (indole) : n (pyruvic acid) = 0.6:1. In 100 mL reaction mixture which contained 0.57 mol/L of pyruvic acid, after 28 h, the concentration of L-tryptophan synthesized by tryptophanase whole cell was 0.25 mol/L, by adding 6.5 mL 4.27 mol/L of indole alcohol solution. And, the mole conversion rate of indole was up to 91.8%. This study increases the catalytic activity of tryptophanase, provides a low-cost pyruvate substrate source, and provides a useful reference for industrial production of L- tryptophan.