Abstract: Objective To explore the platelet reactivity and its influencing factors in patients with chronic kidney disease（CKD）and acute coronary syndrome（ACS）after percutaneous coronary intervention（PCI）. Methods From January 2019 to August 2021，40 ACS patients with CKD receiving PCI were selected as observation group. Another 40 ACS patients receiving PCI during the same period were assigned into control group. All patients received standard dual antiplatelet therapy. During normal dosing，platelet reactivity was measured by LTA method and platelet aggregation rate induced by ADP compared between two groups. Spearman’ s linear equation was utilized for examining the correlation between platelet aggregation rate induced by ADP and severity of CKD. ADP-induced platelet aggregation rate >40% was defined as high platelet reactivity（HPR）. Based on the results，it is divided into two groups of HPR and non-HPR. Clinical data of two groups were compared. Multi-factor Logistic regression equation was employed for examining the related factors of HPR. Results Platelet aggregation rate induced by ADP was significantly higher in observation group than that in control group［（38.41±8.79） % vs（23.34±9.81） %］and the difference was statistically significant（P<0.05）； with greater severity of CKD，platelet aggregation rate induced by ADP gradually rose（F_Trend=13.456，P<0.05）； Spearman’ s linear correlation analysis indicated that ADP-induced platelet aggregation rate was positively correlated with severity of CKD（ρ=0.640，P<0.05）；age，proportion of type 2 diabetes mellitus （T2DM），proportion of vascular disease ≥3 and ratio of CKD were significantly higher in HPR group than those in non-HPR group；levels of hemoglobin and 25 hydroxyvitamin D were lower in HPR group than those in non-HPR group（P<0.05）；Multivariate Logistic regression analysis revealed that T2DM （OR=8.641）and vascular disease ≥3 vessels（OR=10.205）were independent risk factors for HPR in ACS patients after PCI（P<0.05）. For CKD patients，T2DM（OR=7.640），vascular lesions ≥3（OR =13.098），low hemoglobin（OR=0.968）and low 25 hydroxyvitamin D（OR=0.674）were the independent risk factors of HPR in ACS patients after PCI（P<0.05）. Conclusion As compared with nonCKD counterparts，CKD patients with ACS have higher platelet reactivity after PCI. And it is positively correlated with severity of CKD. Anemia due to CKD and low vitamin D are also independent risk factors for HPR.