Abstract: The acute toxicities of 7 chloroanilines,i.e.2-chloro-4-nitroaniline,4-chloro-3-nitroaniline,2-chloro-5-nitroaniline,2,4-dichloroaniline,3,4-dichloroaniline,2,5-dichloroaniline and 2,3-dichloroaniline,to zebra fish ( Brachydanio rerio) were studied,and the 96 h LC 50 were 6.99,2.58,8.63,7.79,6.08,5.23 and 0.49 mg/L respectively.3D-QSAR analysis of these chemicals was conducted to study the relationship between molecular structure and biological activity (toxicity),and the observed values were well correlated with the calculated ( R² =0 907).