Abstract: Objective: To investigate the different characteristics in patients with primary and secondary Sjogren's syndrome（SS）,in order to provide new information for diagnosis of SS.Methods: 44 primary Sjogren's syndrome（pSS） and 37 secondary Sjogren's Syndrome（sSS） patients were enrolled（17 patients secondary to SLE,SS-SLE and 20 patients secondary to RA,SS-RA）.The different clinical features and laboratory examination in patients with pSS and sSS were compared.Results: The mean age at onset was（45.3±11.7）ys in pSS and was（42.9±11.7）ys in SS-SLE and was（53.2±13.8）ys in SS-RA respectively,pSS patients were younger than those with SS-RA（P=0.02）.We found higher percentage of fever,labial gland biopsy and anti-SS-A/B antibodies in pSS patients than those with SS-RA and higher percentage of dental necrosis than those with SS-SLE（P＜0.05）.More proteinuria and renal tubule acidosis were found in SS-SLE patients than those in pSS（P=0.000,P=0.06）.More arthralgia was found in SS-RA patients than those with pSS.More parotid gland enlargement was found in pSS patients than in the sSS ones（P=0.003）.PSS presented a lower prevalence of peripheral neuropathy and hemoglobin than sSS patients（P=0.044,0.045）.The frequency of the decreasing of white blood cell,serum K and C3 in SS-SLE and rheumatoid factor and c-reactive protein in SS-RA patients were higher than those of pSS.The granular pattern of ANA was the most common pattern in pSS and sSS.Besides,nucleolar pattern and nuclear membrane pattern were more often in pSS cases,and homogeneous pattern and kytoplasm pattern were more often in sSS.Conclusion: Compared with patients with pSS and sSS,the pSS patients were younger than SS-RA ones in disease onset and clinical features tend to be more typical.PSS patients may have more common parotid gland enlargement and present less frequently to have proteinuria,anaemia,C3 decreasing and peripheral neuropathy.More nucleolar pattern and nuclear membrane pattern were found in pSS.