Disclosed in the present invention is a method for preparing Ticagrelor (I), comprising the following steps: a cyclization reaction of 5-amino-1,4-di-substituted-1,2,3-triazole (II) and dialkyl carbonate (HI), to obtain 9-substituted-2,6-dihydroxy-8-azapurine (IV); chlorination of intermediate (IV), to obtain 9-substituted-2,6-dichloro-8-azapurine (V); an amination reaction of intermediate (V) and trans-(1R,2S)-2-(3,4-difluorophenyl)cyclopropanamine (VI) generates 9-substituted-6-amino-substituted-2-chloro-8-azapurine (VII); and a propanethiolation reaction of intermediate (VII) and propanethiol (VIII), to obtain Ticagrelor (I). The preparation method is simple in process, has a high chemical and chiral purity and provides a new preparation method for industrializing Ticagrelor. In addition, also provided in the present invention are intermediates of Ticagrelor and a preparation method thereof, wherein raw materials of the preparation method are easily available, the conditions thereof are mild, and the yield thereof is high.