Introduction: The incidence of lung cancer and acute ischemic stroke remains high in recent years, both of which occur mostly in people over 60 years old. In the present study, we aimed to further clarify the pathogenesis of lung cancer-associated acute ischemic stroke (LCA-AIS) by comparing and analyzing clinical characteristics of stroke patients with or without lung cancer. Methods: A total of 51 patients with lung cancer were selected as the case group (LCSG), and 78 patients without cancer history were adopted as the control group (SG). The data collected in this study included sex, age, traditional cerebrovascular disease risk factors (TCDRFs), blood test index, imaging findings, etiological typing, and prognosis evaluation. SPSS21.0 software was used for statistical analysis. Normally distributed data were analyzed by t-test, and count data were analyzed by chi-square test or exact probability method. P < 0.05 was considered statistically significant. Results: In the case group, the levels of plasma D-dimer, fibrinogen degradation products (FDPs) and NIHSS, as well as the mRS score and mortality of patients, were higher, while the levels of RBC, Hb and Hcy were lower compared with the control group. Imaging findings showed that multivessel involvement was more common in the case group, and the infarcts were more likely to be multiple and involved in both the anterior and posterior circulations. The TOAST classification of LCSG was dominated by stroke of undetermined etiology (SUE) and stroke of other determined etiology (SOE). Statistical analysis showed that the patients were more likely to suffer from acute ischemic stroke within 1 year after the diagnosis of lung cancer (41 cases, 80.39%). Conclusions: Hypercoagulability and acute multiple brain infarcts were more common in patients with LCA-AIS, and hypoproteinemia and hyponatremia were more likely to occur in these patients, leading to worse prognosis. Patients were most likely to have a stroke within 1 year after the diagnosis of lung cancer.