In order to explore the application status and influencing factors of doctor-patient shared decision-making in the treatment of malignant tumor diseases to construct a theoretical model of influencing factors. The semi-structured interview method was used to conduct in-depth interviews with doctors and patients in a large top-three hospital in Jiangsu Province. Based on the grounded theory, the interview text was coded at the three levels by Nvivo20.0 software. Finally, 47 concepts, 20 sub-categories and 9 main categories are summarized and sorted out. With "environment", "patient", "doctor" and "decision" as the four core categories, and external environment, medical system, patients" willingness to participate, patients" personal characteristics, decision-making cost, decision-making ethics, decision-making information, doctors" attitude and doctors" ability as the nine main categories, the theoretical model of influencing factors of doctor-patient shared decision-making in the treatment of malignant tumor diseases is formed. The implementation of doctor-patient shared decision-making is affected by multiple factors. The government needs to create a good information environment through laws and regulations, effectively communicate between doctors and patients, deeply understand the demands of both sides, respect the rights and interests of patients, and gradually bridge the gap caused by information inequality to improve medical satisfaction.