To explore the current application status and influencing factors of doctor-patient shared decision-making in treating malignant tumor diseases，this study aimed to construct a theoretical model of these influencing factors. The semi-structured interview method was used to conduct in-depth interviews with doctors and patients in a sizable top -three hospital in Jiangsu Province. Based on the grounded theory，the interview text was coded at the three -level coding by Nvivo 20.0 software，resulting identifying，47 concepts，20 sub-categories，and 9 main categories summarized and sorted out. Four core categories identified with“environment” “patient”“doctor”and“decision”，and nine external environment categories were healthcare system，patient participation willingness，personal characteristics，decision-making cost，decision-making ethics，decision-making information，and doctors’attitude ability. These factors form the theoretical model of influencing factors of doctor-patient shared decision -making in treating malignant tumor diseases. The implementation of doctor-patient shared decision-making is affected by multiple factors. The government needs to create favorable information environment through laws and regulations，and effectively communicate between doctors and patients to deeply understand the demands of both sides and therefore respect the rights and interests of patients，and gradually bridge the gap caused by information inequality to improve medical satisfaction.