Abstract:The diagnosis of diseases in Tibetan medicine is generally divided into three methods: look, smell and touch. Tentative diagnosis method is a comprehensive diagnostic method, which can be diagnosed by observing the patient's response, urine, tongue image and changes of the disease after internal and external use of drugs, or by directly detecting the patient′s urine and saliva to diagnose the disease. This paper collects 100 tentative diagnostic methods from 15 representative ancient books of Tibetan medicine in different periods. According to the analysis in order of historical sequence, the application proportion of tentative diagnostic method in the classification of diseases of Tibetan medicine in the "the fifteen divisions" is calculated, and it is found that tentative diagnostic method is first recorded in the 8th century ancient books of Tibetan medicine, such as smgn dbyd zla rgayl and bi ji bo ti ka ser. Along with the development of Tibetan medicine, tentative diagnostic method has always been its development trend. It is mainly used in clinical diagnosis of poisoning, trauma, pathogenic disease, fever and other difficult to identify diseases, scientific nature is very strong, and it has significant diagnostic benefits for difficult diseases.