E. coli EP8-10 was selected from the soil. It was able to produce the transaminase with high activity when it was cultivated on the medium containing peptone and beef extract. Optimum conditions of enzyme reaction was: phenylpyruvic acid's concentration of 013～015mol/L, L-Asptaric acid used as amino donor, pH8. 537℃. When phenylpyruvic acid was 0.3mol/L, 48g/L L-phenylalanine was produced after 6h with 97% conversion rate.