The method of thymopentin nasal spray's preparation was studied and the method of thymopentin nasal spray's quality control was established. The composition of the formulation and its preparation technol. are presented. The content of thymopentin is tested by UV spectrophotometry. The average recovery of thymopentin is 100.06%, RSD = 0.13% (n = 5), and the method of content test is feasible enough. The thymopentin nasal spray's preparation is very easy, the method of quality control is reliable, and the quality is stable.