Photoacoustic imaging (PAI) has the characteristics of both structural and functional imaging and is a new focus in medical imaging research at present. Its research direction covers microscopic cell molecules and macroscopic tissue and organs. PAI can quantitatively evaluate the oxygen saturation of myoglobin, which can reflect the repair status of damaged muscles; it can also clearly display 2D and 3D structure and morphology of the articular cartilage, synovium, blood vessels, and bone tissue; and the trials with patients affected by inflammatory arthritis have also suggested that PAI can detect the degree of cartilage damage non-invasively. Furthermore, by coupling the antibody with photoacoustic contrast agent, PAI can accurately distinguish the spatial information of molecular markers of inflammation, which is helpful to the diagnosis and staging of arthritis.