NOVELTY - Ticagrelor ((1S,2S,3R,5S)-3-(7-((1R,2S)-2-(3,4-difluorophenyl)cyclopropylamino)-5-(propylthio)-3H-(1,2,3)triazolo(4,5-d)pyrimidin-3-yl)-5-(2-hydroxyethoxy)cyclopentane-1,2-diol) (I) is prepared by reacting cyclopentyl-(d)(1,3)-dioxol-4-yl-carbamic acid ester compound (IX) with dioxolane compound (X); removing amino protecting group of cyclopenta(d)(1,3)(dioxol-4-yl)oxy)-dioxolane compound (VIII) and reacting with pyrimidine compound (XI); reducing and cyclizing; and reacting cyclization product with difluorophenyl-cyclopropylamine compound (XII), removing protection group and reducing.    USE - Method of preparing Ticagrelor used as antiplatelet medicine.    ADVANTAGE - The method has simple, convenient and safe operation, low cost and less pollution, and is suitable for large-scale industrial production.    DETAILED DESCRIPTION - Preparation of Ticagrelor ((1S,2S,3R,5S)-3-(7-((1R,2S)-2-(3,4-difluorophenyl)cyclopropylamino)-5-(propylthio)-3H-(1,2,3)triazolo(4,5-d)pyrimidin-3-yl)-5-(2-hydroxyethoxy)cyclopentane-1,2-diol) of formula (I) comprises:    (A) reacting cyclopentyl-(d)(1,3)-dioxol-4-yl-carbamic acid ester compound of formula (IX) with dioxolane compound of formula (X) under action of alkali to prepare cyclopenta(d)(1,3)(dioxol-4-yl)oxy)-dioxolane compound of formula (VIII);    (B) removing amino protecting group of compound (VIII) and reacting with pyrimidine compound of formula (XI) under action of alkali to obtain cyclopentyl-(d)(1,3)-dioxol-pyrimidine compound of formula (VI);    (C) subjecting compound (VI) to reduction reaction and performing alkali metal nitrite cyclization reaction;    (D) reacting cyclization product with difluorophenyl-cyclopropylamine compound of formula (XII) or its salt to obtain intermediate product; and    (E) removing protection group of intermediate product and performing reduction reaction to obtain compound (I).    R1, R2=H or 1-8C alkyl; or    R1R2=4-8C spiro ring;    R3=trityl, benzyl, 4-methyl benzyl, 4-nitryl, 2,4-dimethoxy benzyl, benzyloxycarbonyl (Cbz), 4-methoxybenzyloxycarbonyl, or 4-methylbenzyloxycarbonyl;    R4, R5=1-8C alkyl; or    OR4R5=ring-(CH2)n-;    n= less than or equal to 7;    X, Y'=halo, R6C(O)O acyloxy, or R7S(O2) carbamate;    R6=1-6C alkyl, CF3 or aryl; and    R7=1-6C alkyl, 1-6C fluoroalkyl, or aryl.