Less veterinary drug use is an important measure to realize the green development of modern agriculture. Based on the micro survey data of 466 broiler farmers in Liaoning Province,and the Damage Control Model relying on the Weibull distribution function,this paper evaluated broiler farmers’ excessive application behavior of veterinary drugs and explored the influencing factors by the OLS model and the Probit regression model from the following four perspectives:government regulations,market profits assurance,industrial organization modes,and socialized services. The results showed that the overuse of veterinary drugs was quite common in the surveyed areas,which could be expounded by specific figures below. The proportion of surveyed broiler farmers using veterinary drugs excessively accounted for 60.52% of the whole,and the overuse level was 24.84% higher than the optimal level. Model regression results showed that these factors,including breeding supervision,inspection and quarantine,cooperation participation,vertical integration,technical training,information services,and breeding scale,had significant positive influences on decreasing the application of veterinary drugs; while the concern about possible decline of production had significant negative influences. These findings suggest that the inspection and quarantine management and the supervision of production should be strengthened; the segmented chicken product marketing system should be improved; the mechanism to support the high-quality and inexpensive chicken should be established; new agribusiness entities should be nurtured; organizational levels of broiler farmers should be upgraded; more technical training and information services should be provided.