Background Graded diagnosis and treatment is one of the main goals of medical reform. In 2015, the General Office of the State Council issued the"Guiding Opinions on Promoting the Construction of Graded Diagnosis and Treatment System" (Guo Ban Fa[2015]No. 70), which stated that in 2017, the proportion of diagnosis and treatment in grassroots medical institutions was over 65.0%, but that proportion was 54.2% that year, and in recent years, it has shown an overall downward trend. Previous literature has mostly focused on the demand side (patients) for research, while as one of the suppliers of graded diagnosis and treatment, there have been few surveys on the willingness of general practitioners to participate in graded diagnosis and treatment. Objective This article aims to take Suzhou City as an example to investigate and study the willingness of general practitioners to participate in graded diagnosis and treatment, analyze its influencing factors, and provide suggestions to improve the willingness of general practitioners to participate in graded diagnosis and treatment, providing reference for formulating policies related to graded diagnosis and treatment. Methods In June 2022, a multi-stage convenient sampling method was adopted to select 1 451 general practitioners from 175 grassroots medical and health institutions (hereinafter referred to as grassroots institutions) in 4 counties and 6 districts of Suzhou City. A self-developed survey questionnaire was used to conduct the survey. The questionnaire includes the survey of general practitioners' basic situation (demography characteristics), survey of general practitioners' willingness to participate in hierarchical diagnosis and treatment (this part of the questionnaire is based on the expanded model of influencing factors of general practitioners' willingness to participate in hierarchical diagnosis and treatment, which is a fusion model of theory of planned behavior (TPB) and technology acceptance model (TAM) combined with Document retrieval and interview collection content). According to the survey results, use structural equation model SEM analysis to test the influencing factors of general practitioners' willingness to participate in graded diagnosis and treatment, expand the model's fit, and determine the model's fit effect. Exploratory factor analysis was used to calculate the weight (influence) of each influencing factor of general practitioners' willingness to participate in graded diagnosis and treatment, and to build a Relational model of influencing factors of general practitioners' willingness to participate in graded diagnosis and treatment. Results One thousand four hundred and fifty-one general practitioners participated in this questionnaire survey, and 1 302 valid questionnaires were collected, with an effective rate of 89.73%. The expanded model of influencing factors on the willingness of general practitioners to participate in graded diagnosis and treatment is well fitted. In the influencing factors of general practitioners' willingness to participate in graded diagnosis and treatment, participation attitude, subjective norms, and perceived behavioral control jointly affect the willingness of general practitioners to participate in graded diagnosis and treatment, with weights of 46.22%, 9.75%, and 44.02%, respectively. Perceived benefits and perceived usefulness jointly explain participation attitudes, with weights of 15.14% and 31.08% respectively. Disposable resources and expected resistance jointly explain perceptual behavioral control, with weights of 27.07% and 16.95%, respectively. Conclusion The degree of recognition of the medical service capabilities of higher-level hospitals by general practitioners, the complexity of referral procedures, and the degree of openness of medical resources from higher-level hospitals to general practitioners have a significant impact on the willingness of general practitioners to participate in graded diagnosis and treatment. It is recommended to strengthen communication and interaction among personnel within the medical association at the administrative, organizational, and personal levels, and use information technology to simplify referral processes and procedures Encourage higher-level hospitals to provide targeted and quantitative access to medical resources such as outpatient number sources and ward beds for general practitioners, and take various measures to increase their willingness to participate in graded diagnosis and treatment.