Objective:To explore the associations of platelet parameters platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW) and plateletcrit (PCT) with the risk for stroke in people with different blood pressure levels.Methods:All the participants were from Dongfeng-Tongji cohort, including 38 295 retired employees from Dongfeng Motor Corporation at the first follow-up survey. After excluding participants with coronary heart disease, stroke, cancer, history of platelet influential drug use and those with missed data of platelet parameters or blood pressure or lost to follow-up, finally a total of 21 294 participants were included in this study. All the participants completed baseline questionnaires, physical examinations, clinical biochemical tests, and blood sample collection. Cox proportional hazard models were used to estimate the hazard ratios ( HRs) and the corresponding 95% confident intervals ( CIs) for the associations between platelet parameters and risk for stroke in people with different blood pressure levels. Results:After a mean follow-up of 8.0 years, 1 578 participants developed incident stroke [1 266 ischemic stroke (IS) cases and 312 hemorrhagic stroke (HS) cases]. Compared with the participants with PLT<188×10 9/L, those with PLT≥188×10 9/L among hypertension cases were significantly associated with higher risks for stroke and IS (stroke: HR=1.27, 95% CI: 1.12-1.44; IS: HR=1.39, 95% CI: 1.21-1.60). Among hypertension group, compared with participants with PCT<0.165%, PCT≥0.165% were significantly associated with higher risk for stroke ( HR=1.15, 95% CI: 1.01-1.30) and lower risk for HS ( HR=0.70, 95% CI: 0.53-0.93); Among non-hypertension and hypertension group, PCT ≥0.165% were significantly associated with higher risks of IS ( HR=1.27, 95% CI: 1.05-1.54; HR=1.31, 95% CI: 1.14-1.50). MPV and PDW were not significantly associated with risk for stroke. Risk for stroke increased significantly in hypertension cases with different platelet parameters levels compared with non-hypertension cases with lower levels of each platelet parameters. Conclusion:Higher levels of PLT and PCT could increase the risks for stroke and IS in middle-aged and elderly hypertension patients, and lower levels of PCT could decrease the risk for HS in hypertension patients.