The present invention relates to a formulation of ticagrelor or a pharmaceutically acceptable salt thereof. Specifically, the present invention relates to an improved formulation of ticagrelor or a pharmaceutically acceptable salt thereof, which is administered once a day. In the present invention, the plasma concentration of ticagrelor in a subject is greater than about 0.2 μg/mL within 2 hours; and the plasma concentration of ticagrelor in a subject is greater than about 0.2 μg/mL at 12 hours after administration; and the maximum plasma concentration (Cmax) of ticagrelor or a pharmaceutically acceptable salt thereof in a subject is between about 0.2 μg/mL and about 0.8 μg/mL. The formulation of the present invention can reduce the frequency of administration, thereby improving patient compliance and reducing the risk of myocardial infarction or stroke induced by acute thrombosis which is caused by missed administration of ticagrelor.