Quinolones -typical pyrazole in drinking water are often exposed to the Isopropylphenazone (PRP) as the research object, investigated with variation of acute toxicity of water and the genetic toxicity of PRP before and after chlorination of drinking water. The results of acute toxicity test showed that Chlorella, different concentrations of PRP (0, 0.004, 0.009, 0.017, 0.035, 0.069, 0.139 mmol/L) exposure conditions, the Chlorella growth inhibition rate showed obvious dose effect relationship, with the increase in the concentration of PRP exposure, chlorella growth inhibition rate increased in the high dosage of chlorine; (the concentration ratio of PRP and 1:2 and 1:5 Moore chloride), inhibition on the growth of Chlorella water after chlorination rate was higher than that in low chloride before disinfection, chlorine dosage (concentration ratio of PRP and 4:1 and 1:1 Moore chloride), water samples of chlorella growth inhibition rate was below the chlorination, show low chlorine dosage can reduce the risk of acute toxicity of water produced by PRP. The results of genetic toxicity test showed that the SOS/umu, both with and without exogenous metabolic enzymes S9, PRP showed a good dose-response relationship, the induction ratio (IR value) increases with the increasing of PRP concentration, but overall genetic toxicity is relatively small (IR<1.5); PRP in the chlorination process. The IR value increased with the increase of the amount of chlorine and gradually become larger, direct and indirect genotoxicity toxicity equivalent of TEQ4-NQO and TEQBaP etc. were increased, showed that the direct genetic toxicity of PRP containing drinking water