The PRINCE trial is a prospective, randomized, multi-centre, open-label, active-controlled, blinded-endpoint trial (a PROBE design concerning clinical trial). A total of approximately 952 patients (40years≤Age＜80years) with high-risk TIA (defined as an ABCD2 score ≥ 4 or the stenosis of offending vessel ≥ 50%) or minor ischemic stroke (defined as an NIHSS ≤ 3), who can be treated within 24 hours of symptom onset will be enrolled. Patients fulfilling all of the inclusion criteria and none of the exclusion criteria will be randomized 1:1 into two groups after offering informed content: 1) one group will receive a 180 mg loading dose of ticagrelor on the day of randomization, followed by 90 mg twice/day ticagrelor from Day 2 to 3 months; 2) the other group will receive a 300 mg loading dose of clopidogrel on the day of randomization, followed by 75 mg once/day clopidogrel from Day 2 to 3 months. Aspirin will be given in a total dose of 100-300 mg on the first day, followed by 100 mg once/day from Day 2 to Day 21 in the both groups. The primary objective is to assess the anti-platelet effects of Ticagrelor combined with Aspirin versus Clopidogrel combined with Aspirin in Chinese patients with high-risk TIA and minor stroke. The study consists of six visits including the day of randomization, 2 hours after the first anti-platelet agents, 24 hours after the first anti-platelet agents, Day 7+2days, Day 21±2days and Day 90±7days. Genomic DNA of all patients will be collected for genotyped. And the genetic variants affecting Clopidogrel metabolism will be analyzed. The antiplatelet effects will be analyzed in total subjects and genetic variants carriers. The trial is anticipated to complete in 18 months from the first subject recruitment , with 952 subjects recruited from 25 centres in China. A Data and Safety Monitoring Board (DSMB) will regularly monitor safety during the study. The trial has been approved by IRB(Institutional Review Board) /EC(Ethics Committee) in Beijing Tiantan hospital, Capital Medical University.