Effects of different pressures( HP,100 ~ 500 MPa) and different temperatures( 25 ~ 70℃) on product specificity of α-CGTase were studied. Results showed that the product specificity of α-CGTase increased a lot under 40℃ and 200MPa while enzyme activity and the product yield maintained very high. It was found that the product specificity of α-CGTase increased with the increase of pressures on α-CGTase at 40℃. When the pressure was under 200MPa,the cyclic activity of α-CGTase increased slightly with the increase of pressures,but it reduced rapidly if the pressure was above 200MPa. At the pressure of 200MPa,the cyclic activity was the highest( 62. 49U / mL) at 25℃ and the product specificity was the highest( 55. 9%) at 40℃. In addition,the product specificity of α-CGTase reduced with the prolonged reaction time.