The tyrosine phenol lyase (TPL) from Citrobacter freundii was recombinantly expressed in E. coli BL21 (DE3) with the vector pETDuet-1. The enzymatic properties of recombinant tyrosine phenol lyase were studied, and several influence factors of enzyme reaction such as pH, temperature, surfactants, metal ions, ammonium salts, and ammonium chloride concentration were investigated. The result indicate that the optimum reaction condition of TPL were 45℃, pH 8.0, 4 mmol/l PLP, 350 mmol/l NH4Cl, 1 mmol/l triton-x 100. The conversion rate of pyruvate substrate was 1.8 times higher than that of serine substrate.