Abstract: Objective: To explore the application effects of QCC in improving the qualified rate of self-injection of insulin in hospitalized patients with diabetes mellitus in department of endocrinology. Methods: We conducted QCC activities in the department, and analyzed the reasons for the low qualified rate of self-injection of insulin in hospitalized patients with diabetes, then developed and implemented countermeasures. Results: The qualified rate of self-injection of insulin in hospitalized patients with diabetes improved from 20.9% to 63.2%. Conclusion: Through the continuous improvement of the QCC activities, the qualified rate of self-injection of insulin in hospitalized patients with diabetes has significantly improved, and the nurse-patient and doctor-patient relationship become closer.