Abstract: A new method for determining transaminase activity based on the color change of the reaction solution was established, by using alanine-dependent transaminase VfTA from Vibrio fluvialis JS17 as the research object coupled with pyruvate oxidase and horseradish peroxidase. After the optimization of the conditions, the linear relationship between VfTA activity units and the absorbance at 400 nm was investigated. This method was also applied to determine the activity of commercial transaminase ATA117. The results showed that the detection limit of transaminase VfTA activity was up to 0. 45 U/mL and the detection limit of ATA117 activity was up to 0. 5 U/mL. The transaminase activity could be quickly judged according to the color depth of the reaction solution.