To investigate the prognostic value of platelet-to-neutrophil ratio (PNR) in acute ischemic stroke (AIS) patients. In this study, a total of 400 AIS patients were included. Demographic, clinical, laboratory data were collected on admission, and PNR was calculated according to platelet and neutrophil counts on admission. The prognosis after 3 months was evaluated by the Barthel index (BI), where BI ≤85 was defined as poor prognosis and BI >85 was defined as good prognosis. Regression analyses were performed, adjusting for confounders. (1) Compared with good prognosis group, PNR level on admission in poor prognosis group was significantly lower, the difference between the two groups was statistically significant (P < 0.05). (2) The difference in PNR level between the large infarct volume group and small infarct volume group was no statistically significant, nor between the moderate to severe group and the mild group (all P > 0.05). (3) In multivariate logistic regression analysis, PNR, platelet-to-lymphocyte ratio (PLR), platelet-to-white blood cell ratio (PWR) level were correlated with the 3 month prognosis of AIS. PNR may be an independent protective factor for predicting the prognosis of AIS. PNR level has a higher accuracy in the 3 month prognosis of acute ischemic cerebral infarction than the level of PLR and PWR. The level of PNR is correlated with the 3 month prognosis of acute ischemic cerebral infarction. The level of PNR may be an independent protective factor for predicting the prognosis of AIS.