1. A process of evaluating blood-brain barrier permeability of a rat model of stroke by using a fluorescent substance, the process comprising: injecting an Evans blue dye into a rat model of stroke, wherein the rat model of stroke has been subjected to middle cerebral artery occlusion; detecting the fluorescence distribution in the whole brain by using a non-invasive in vivo imaging system; and obtaining both fluorescence images and optical images for the whole brain tissue.