In vivo imaging refers to the qualitative and quantitative study of biological processes at the tissue, cellular and molecular levels in the living state. In vivo imaging technology can be divided into five types, including optical imaging, positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT) imaging and ultrasound imaging. Among them, optical imaging (also called functional imaging) is particularly suitable for studying molecular, metabolic and physiological events. Moreover, optical in vivo imaging can be divided into bioluminescence in vivo imaging and fluorescence in vivo imaging. Bioluminescence in vivo imaging is the labeling of cells or DNA with luciferase genes, while fluorescence in vivo imaging uses fluorescent reporter groups (such as GFP, RFP and so on) for labeling.