Objective: To explore the influencing factors for implementation of weight management services in primary medical and healthcare institutions, so as to provide references for implementing sustainable services of weight management. Methods: From May to June 2025, Pinghu City, Zhejiang Province was selected as the survey site. Personnel responsible for weight management in primary medical and healthcare institutions were selected as the survey subjects using a combined method of purposive sampling and snowball sampling. Based on the five core domains of the consolidated framework for implementation research (CFIR), a semi-structured interview outline for weight management services in primary medical and healthcare institutions was designed. Original data was collected through face-to-face semi-structured interviews. Interview data was organized and analyzed using framework analysis. Factors affecting weight management services were quantitatively analyzed by referencing CFIR's structural rating criteria. Results: A total of 21 participants completed interviews, covering positions in nutrition, endocrinology, traditional Chinese medicine, general practice, maternal health, and public health. There were 9 males and 12 females. Fifteen participants (71.43%) were aged 35 years and above, 18 (85.71%) held a bachelor's degree or higher, and 15 (71.43%) were frontline medical staff. Fifteen factors affecting weight management services were identified across five domains: innovation, outer setting, inner setting, individuals, and implementation process. Six barrier factors were identified: difficulties in policy implementation, time-consuming interventions, limited incentive measures, lack of professional skills, unclear weight-loss plans and goal setting, and imperfect follow-up and evaluation mechanisms. Three neutral factors were identified: the development and refinement of policies and regulations, the implementation of weight management training, and the optimization of the referral process within integrated healthcare systems (medical alliances / communities). Six facilitating factors were identified: the relatively significant advantages of lifestyle interventions, collaboration and coordination across multiple departments, cooperative communication among different units within the institution, the inherent convenience of primary care settings, a strong sense of professional responsibility, and the establishment of multidisciplinary teams. Conclusions The delivery of weight management services in primary medical and healthcare institutions is influenced by a wide array of factors across multiple domains. It requires policy support, multi-department coordination, a practice-oriented training system, optimized team resource allocation, incentives, and improved professional skills of medical staff to jointly promote long-term implementation.