Abstract: This paper reports on the degradation of phenols and anilines using hydrogen peroxide as oxidizer and enzyme from Serratia marcescens Y-SM01 as catalyst. First, the COD_Cr values before and after degradation were measured. Then, changes of molecular structures during the process were investigated with UV-VIS, IR and HPLC. It was found that after degradation, for some compounds such as hydroquinone, peaks on UV-VIS and IR spectra which belong to phenyl ring all disappeared, and HPLC found small molecules such as organic compounds. So the mechanism was clarified that in the degradation the phenyl ring was cleaved and small molecules were introduced, which just caused the COD_Cr values of degradable compounds such as hydroquinone to decline greatly. Also, the connection between degradation properties and structures of phenols and anilines was analyzed, and the conclusion was as follows: di-/tri-phenols/anilines were easier to degrade than mono-phenols/anilines; ortho-/para- substituted compounds were easier to degrade than meta- substituted compounds; electron-attracting substituents such as —OH, —NH₂, —OCH₃ made degradation easier, while electron-withdrawing substituents such as —NO₂, —Cl, —COOH made degradation more difficult.