To analyze the correlation between sleep quality, cognitive impairment and serum C-reactive protein (CRP) in patients with ischemic stroke.Methods 160 patients with acute ischemic stroke treated in our hospital from May 2018 to May 2020 were selected as the research object. According to the level of serum CRP, 80 patients were divided into 80 cases in the study group (increased serum CRP group) and 80 cases in the control group (normal serum CRP group). Epwoeth sleepiness scale (ESS),insomnia severity index (ISI) and Pittsburgh sleep quality index (PSQI) were used to evaluate the sleep quality of the two groups, and Montreal Cognitive Assessment Scale (MoCA) and mini mental state examination scale (MMSE) were used to evaluate the cognitive function of the two groups; The levels of serum CRP in the two groups were detected by enzyme linked immunosorbent assay. Pearson correlation test the correlation between sleep quality, cognitive impairment score and serum CRP in the study group. Results The scores of ESS and PSQI in the study group were significantly higher than those in the control group (P＜0.05). In all items of PSQI scale, the scores of sleep disorder and daytime dysfunction in the study group were significantly higher than those in the control group, and the scores of sleep latency and sleep duration were significantly lower than those in the control group (P＜0.05). The total score of Moca, visual space and executive function, language, abstraction and memory in the study group were significantly lower than those in the control group (P＜0.05). In the MMSE scale score, the total MMSE score, computational power, delayed recall and language ability in the study group were significantly lower than those in the control group (P＜0.05). The level of serum CRP in the study group was (17.21±3.87) mg / L, which was significantly higher than that in the control group (1.16±0.54) mg/L (P＜0.01). The total scores of ESS, PSQI, sleep disorder and daytime dysfunction in patients with ischemic stroke were positively correlated with serum CRP (P＜0.05), and the sleep latency, sleep duration and sleep efficiency were negatively correlated with serum CRP (P＜0.05). The total score of MOCA scale, MMSE scale and the scores of various items in patients with ischemic stroke were negatively correlated with serum CRP (P＜0.05). Conclusion There is a significant correlation between serum CRP level and sleep quality and cognitive impairment in patients with ischemic stroke. The higher the CRP level, the more serious the cognitive impairment and the lower the sleep quality, which can be used as a biomarker in the disease process of patients with ischemic stroke.