Objective To explore the effect of online learning and offline practice of positive psychology on work stress and health of clinical nurses. Methods A total of 101 nurses with severe work stress were divided into a control group (n=50) and an experimental group (n=51) according to branches of hospital where they work. Both groups received routine psychological support, while the experimental group was additionlly provided with online training of positive psychology and offline practice for 12 weeks. The Work Stressors for Nurses and the Cornell Medical Index were utilized to survey before and after the intervention. Results After the intervention, the total work stress score and scores of all dimensions of the experimental group were significantly lower than the control group, and the mental health score was also significantly lower than the latter (all P<0.05). Conclusion Online learning and offline practice of positive psychology can relieve work stress of clinical nurses and improve their mental health.