Background The phenomenon of "no referral" still exists against the backdrop of implementing the hierarchical medical system, which has been preliminarily constructed in China. Most existing studies on addressing this phenomenon are mostly from the perspective of hospital management policies, ignoring the role of doctors as "health gatekeepers" in making decisions during the hierarchical diagnosis and treatment process. Objective To investigate the influence of personal, institutional, environmental, and policy factors on the willingness of physicians in county hospitals to refer patients with common diseases to lower level of institutions from physicians' perspective. Methods This study was conducted from July to August 2021. By use of region-based stratified and convenience sampling, seven county-level people's hospitals were selected as settings from eastern, central and western China. By use of cluster sampling, physicians (n=142) in internal medical departments were selected from the above-mentioned hospitals to attend an online (through the WJX.cn platform) or off-line (hospital) questionnaire survey to understand their willingness to refer patients with a common illness to lower level institutions, and personal, institutional, environmental, and policy factors associated with their willingness during a consultation described using the scenario simulation method. The survey achieved a response rate of 96.5% (137/142). Binary Logistic regression was used to analyze the effects of personal, institutional, environmental, and policy factors on physicians' willingness to refer the patients to a lower level institution. Results The mean score of physicians' willingness to refer the patients to a lower level institution was (9.92±2.20). Fifty-six physicians (40.9%) had higher level of willingness to conduct downward referrals. Education level, awareness level of referrals, and frequency of communication of referrals between higher and lower level institutions were associated with scores of physicians' willingness to conduct downward referrals (P
