The research studied enhanced treatment of sewage from discharging points of rivers by biofilm process dosing with enzyme and the effect of phenol on removal rates of the main pollution indexes, and investigated promotion effect of enzyme (including the laboratory developed compounded enzyme and the foreign composite enzyme) on treatment of sewage by biofilm process. The research results indicated that when initial concentration of phenol was 1mg/L, the removal rate of phenol in three reactors was above 97%, and phenol had no negative effect on the removal rates of CODCr and ammonia nitrogen, which indicated that phenol (1mg/L) had no poisonous effects on microorganisms. Moreover, enzyme had good promotion effect on biofilm process during the sewage treatment process.