The influencing factors affecting pig farmers to adopt negative behaviors of using veterinary drugs and characteristics of these farmers were analyzed to enhance the accuracy of governmental supervision over farmers’ negative behaviors and reduce safety risks of pig quality. Based on empirical investigation into 654 pig farmers in Funing County，Jiangsu Province，China，the study inspected farmers’ negative behaviors of using veterinary drugs in pig breeding，and analyzed characteristics of these farmers and different levels of their negative behaviors through the Multi-element Orderly Logistic model. Farmers’ negative behaviors of using veterinary drugs are rather common，and these negative behaviors are affected by farmers’ basic characteristics，production and operation characteristics，cognitive characteristics，and governmental supervision characteristics to different degrees. Further analysis on variable marginal effect shows that with other conditions remaining unchanged，male and small-scale farmers engaged in breeding for above 10 years are more likely to use veterinary drugs negatively at the medium level；medium-scale farmers are more likely to use veterinary drugs negatively at the high level；farmers’ educational background and awareness of forbidden veterinary drugs，relative laws and rules，and provisions punishment are in negative correlation with levels of these negative behaviors. Male，small and medium-scale，poorly-educated farmers engaged in breeding for above 10 years should become the major objects of governmental supervision. We should improve farmers’ scientific literacy and public social service systems such as animal product supervision and detection impose rigorous control over slaughter houses，to prevent defective pork from entering markets.