Abstract: Objective To study the onset rule,clinical characteristics and treatment of adult onset Still’s disease（AOSD）. Methods Clinical data about 235 AOSD patients admitted to our hospital in the past 15 years were retrospectively analyzed. Results AOSD occurred in 235 patients at the age of 34.1±12.9 years,and in 54.5% of the patients at the age of 16-35 years,with a female/male ratio of 1.0∶2.3.Fever occurred in all the patients with rash and arthralgia appeared in 90.6% and 86.0% of the patients,respectively.The number of leucocytes was increased in 67.0% of the patients with neutrophils≥80% in 63.9% of the patients.The erythrocyte sedimentation rate（ESR）,C-reactive protein（CRP） and serum ferritin（SF） levels were elevated in 95.7%,93.0% and 57.1% of the patients,respectively.The liver function was abnormal in almost 50% of the patients.The antinuclear antibody（ANA） and rheumatoid factor（RF） were negative in over 90% of the patients.Combined Glucocorticosteroids（GC） plus immunosuppressive agents were used in treatment of 73.2% of the patients with only GC used in treatment of 17.9% of the patients.The number of leukocytes was increased in the patients after treatment with a high dose of GC,which was then decreased to normal in about 10% of the patients within 20 days of treatment and in about 50% of the patients after 20 days of treatment. Conclusion AOSD occurs mainly in young or middle-aged individuals and more in females than in males.Its clinical manifestations include fever,rash and arthralgia.Laboratory findings,such a higher number of WBC and an elevated SF level,are the key points for its diagnosis.AOSD patients are usually treated with GC,but those with their AOSD not easily controlled or frequently relapsed should be treated with combined GC and immunosuppressive agents.The number of leukocytes is gradually decreased to normal after 20 days of treatment with a high dose of GC.