Objective To assess the influencing factors and the prognostic characteristics for the occurrence of mismatch between Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on non-contrast computed tomography (NCCT) and infarct core volume on CT perfusion (CTP) maps in acute ischemic stroke (AIS) patients. Methods Four-hundred and forty-nine AIS patients with large vessel occlusion of anterior circulation who underwent NCCT and CTP evaluation from October 2019 to August 2023 were enrolled retrospectively. NCCT-ASPECTS and infarct core volume on CTP were both calculated by the automated RAPID software. NCCT-CTP mismatch was defined as low ASPECTS with small ischemic core (LASC, ASPECTS< 6 but infarct core volume<70ml) or high ASPECTS with large ischemic core (HALC, ASPECTS≥6 but infarct core volume≥70ml). Favorable clinical outcome after EVT was defined with a mRS score ≤ 0-2 at 90days. The multivariable logistic regression analysis were used to assess the independent influencing factors for NCCT-CTP mismatch. Results Among the enrolled 449 AIS patients, 145 patients presented with NCCT-CTP mismatch and 52 (35.9%) NCCT-CTP mismatch patients achieved good outcomes after EVT. In multivariate logistic regression analysis, the IVT using before baseline imaging (OR, 1.833; 95% CI, 1.205-2.790; P=0.005) and a higher admission NIHSS score (OR, 1.055; 95% CI, 1.028-1.083; P<0.001) were independently associated with the occurrence of NCCT-CTP mismatch for AIS patients. In the subgroup analysis for NCCT-CTP mismatch patients, patients with LASC exhibited longer stroke onset time [median, 306min vs 125min; P=0.004] and a higher rate of hemorrhagic infarction (66.9% vs 33.3%, P=0.021) after EVT than patients with HALC. Conclusions About 35% NCCT-CTP mismatch AIS patients could achieve good outcome after EVT. The IVT using before baseline imaging and a higher admission NIHSS score were independent influencing factors for the occurrence of NCCT-CTP mismatch.