Objective To explore the impact of DRG-based hospital payment system on nursing behavior and its mechanism based on the grounded theory, and to provide reference for nursing practice. Methods A semi-structured face-to-face interview was conducted among 22 nurses who work in hospitals piloting DRGs.Data were collected and analyzed using open, axial and selective coding procedures according to the grounded theory principles. Results A total of 284 initial concepts, 55 initial categories, 16 sub categories and 4 core categories were formed.A theoretical model of the impact of DRG payment system on nursing behavior was developed, including four dimensions of policy incentive, internal motivation, external regulation and nursing behavior. Conclusion Policy incentives have a positive influence on internal motivation of nurses, and affect nursing behavior through external regulation.In order to guide nursing behavior to generate positive outcomes, we should perfect DRG schemes, strengthen monitoring mechanism, optimize nursing performance evaluation system and DRG related training, give priority to nursing quality, and build DRG collaborative management team.