Abstract: The kinetics and mechanism of the enzymatic reaction of phenol and chlorophenol were studied in this paper. It was concluded that oxidative coupling reaction catalyzed by horseradish peroxidase had the characteristic of Ping Pang reaction. The effect of H 2O 2 concentration on the enzymatic reaction was discussed in detail. The results showed that H 2O 2 had an inhibition effect on phenols removal and the inhibition mechanism of H 2O 2 was elucidated. The removal reactions for several substrates were compared according to the kinetics parameters. It was shown that there was a definite relationship between the efficiency of enzymatic reaction and the amount and position of various substituted groups for substrates.