Abstract: OBJECTIVE Proteomic technique was applied to analyze ankylosing spondylitis (AS) patients with damp-heat arthralgia spasm syndrome. METHODS Serum proteins of AS patients with damp-heat arthralgia spasm syndrome group (n=30) was compared with that of normal control group (n=30) and AS patients with cold-dampness arthralgia spasm syndrome group (n=30) respectively by two-dimensional gel electrophoresis; the common differential protein spots of damp-heat arthralgia spasm syndrome were analyzed by the second order MS. The validation of the differential protein was performed using Western blot. RESULTS Seven kinds of common differential protein spots were selected and five kinds of proteins were identified by mass spectrometry. They were fibulin 1， dipeptidy l， peptidase 1， kininogen 1， mutant IL 17F， mannose-binding protein C and related to extracellular matrix protein， protease， coagulation factor， cytokine， transport protein， and so on. Results of Western blot were consistent with the proteomic results. CONCLUSION These proteins are implicated in the pathogenesis and pathological processes of AS with damp-heat arthralgia spasm syndrome， and provide a basis for further studies of the essence of the syndrome in traditional Chinese medicine.