Rat synoviocytes were cultured in vitro and the changing of cellular cytoskeleton induced by PMA was investigated with atomic force microscopy. PMA is usually used to stimulate PKC signal transduction pathway in synoviocytes and to simulate process of inflammation. The results presented here show that synoviocyte cytoskeleton has changed significantly after PKC activation by using the imaging of atomic force microscopy. The results also indicate that the activation of PKC might play crucial role in cytoskeleton changing of synoviocytes，which, to some extent, provides some experiments and ideas on understanding the mechanism underlying rheumatoid arthritis (RA).