Objective:To understand the drug purchase behaviors and prescription flows of outpatients and their influencing factors. Methods: After selecting and investigating tertiary hospitals, secondary hospitals, community health service centers ( one per each level) in Beijing, Zhengzhou, Guangzhou, this paper uses structured question-naire method to analyze 3,155 valid questionnaires. A logistic regression analysis is performed to understand the fac-tors influencing the drug purchase behaviors. Results:The factors influencing the drug purchase behaviors of outpa-tients mainly include the region where the patient is, level of the hospital, type of health insurance that the patient has, frequency of drug purchase, etc. Conclusions: This paper suggests hospital administrators to take measures to improve prescription flows, such as reforming the health care insurance to make payment system more suitable for pharmacies standardizing supply channels in order to make varieties consistent between hospitals and pharmacies, strengthening education and publicity to raise the outpatients’ awareness for drug purchase outside of hospitals, etc.