Abstract: Objective To investigate the application of 3D pseudo-continuous arterial spin labeling (3D-pcASL) perfusion MRI in the diagnosis and thrombolytic therapy of hyperacute cerebral infarction. Methods The clinical data of 7 cases of hyperacute cerebral infarction in our hospital between September, 2014 and April, 2016 were analyzed retrospectively. The magnetic resonance angiography (MRA), diffusion weighted imaging (DWI) and 3D-pcASL perfusion imaging were performed before and after thrombolysis in all cases. Before thrombolysis, the size of lesions and signal characteristics, artery occlusion and blood perfusion was observed; the relationship between blood perfusion and offending artery was evaluated; the scope of lesions on 3D-pcASL and DWI was compared to identify their matching conditions and ischemic penumbra. After thrombolysis, the occluded artery recanalization, size of lesions and blood perfusion change, low or high perfusion was observed. The correlation between blood perfusion, size of lesions and degree of artery recanalization was evaluated. Results Before thrombolysis, MRA displayed middle cerebral artery M₁ segment occlusion in 7 cases, ipsilateral internal carotid artery occlusion in 1 case. DWI showed ipsilateral massive hemispheric high signal area in 7 cases. 3D-pcASL showed large low perfusion area in 7 cases, low perfusion area and artery occlusion was consistent, but it was larger than high signal area on DWI, ischemic penumbra existed. After thrombolysis, MRA displayed middle cerebral artery M₁ segment and its branches recanalization in 5 cases, middle cerebral artery recanalization and distal branches undeveloped in 1 case, middle cerebral artery M₁ segment and ipsilateral internal carotid artery recanalization, middle cerebral artery distal branches undeveloped in 1 case. High signal area reduced on DWI in 7 cases. 3D-pcASL displayed massive hemispheric high perfusion area in 3 cases, low perfusion area reduced in 4 cases, including patchy high perfusion area in 1 case. High or low perfusion area narrowing, high signal area narrowing and degree of artery recanalization was consistent. Conclusion 3D-pcASL can reliably reflect the low blood perfusion of hyperacute cerebral infarction, evaluate ischemia reperfusion and effect of thrombolytic therapy. It is a completely non-invasive magnetic resonance perfusion imaging method.