To observe the curative effect of supplementing qi and nourishing yin method in treating unexplainable fever. Methods： The 38 cases of unexplainable fever patients were randomly divided into treatment group (n=20) and control group (n=18). Patients in treatment group were given symptomatic treatment as well as oral administration of traditional Chinese medicine of supplementing qi and nourishing yin. Patients in the control group only received symptomatic treatment. Course of treatment was15 days. Results： Compared with the control group, the treatment group had significant differences in following aspects： the total effective rate, TCM syndromes, symptom score, temperature stabilization time, average temperature and patients satisfaction on 0, 5th, 10th, 15th day of treatment and the follow-up 10 days after the treatment. The treatment group benefitted more than the control group (P<0.01 or P<0.05). Conclusion： Supplementing qi and nourishing yin method has significant curative effect on unexplainable fever and it enhances patients’ satisfaction, provides a new way for the treatment of unexplainable fever.