Abstract: Objective To investigate clinical characteristics and prognosis in acute ischemic stroke (AIS) patients with paroxysmal atrial fibrillation (AF). Methods We prospectively collected 731 patients with AIS who were hospitalized in the Stroke Unit, First Affiliated Hospital of Harbin Medical University from January to December in 2017. AF and its type were defined according to the patient's disease history, admission electrocardiogram and cardiac monitoring during hospitalization. Follow-up prognostic status at discharge and three months. The clinical features and prognosis of paroxysmal AF group and non-AF group, paroxysmal AF group and persistent AF group were compared. Results ①Compared with AIS patients without AF, patients with paroxysmal AF had more severe neurological impairment at admission (P<0.001). A higher proportion of patients with severe neurological impairment(P=0.002). The proportion of heart failure, coronary heart disease, myocardial infarction, and abnormal renal function was higher (all P<0.05). Increased risk of adverse prognosis at discharge and three months [OR(95% CI)：2.190 (1.111, 4.316), 3.399 (1.701, 6.791)] in patients with paroxysmal AF. ②Compared with AIS patients with persistent AF, patients with paroxysmal AF had a lower proportion of heart valvular disease (P<0.001), and a significantly higher rate of remission during hospitalization (P=0.017). Conclusion Paroxysmal AF patients with AIS have more serious neurological deficits, more associated diseases than AIS patients without AF. Only patients with paroxysmal AF had a lower proportion of valvular heart disease compared with patients with persistent AF. Comparing with patients without atrial fibrillation, paroxysmal atrial fibrillation was a risk factor for discharge and three-months poor prognosis in AIS patients.