Objective: To explore the clinical characteristics and biological treatment of juvenile Idiopathic arthritis (JIA) after adulthood. Methods: Selected 358 patients with previous medical history diagnosed by JIA who were hospitalized in the Department of Rheumatology and Immunology, West China Hospital of Sichuan University from January 1, 2009 to January 1, 2019. Perform retrospective analysis of basic information, clinical symptoms, diagnostic indicators, treatment plans, outpatient follow-up (inpatients require outpatient follow-up treatment) and diagnosis and treatment process of 90 eligible cases included, and observe different ages and different courses of disease. The clinical characteristics of young and middle-aged idiopathic arthritis in adults and the outpatient situation of using biological agents for 6 months. Results: According to age, they were divided into ≤26 years old group (42 cases) and >26 years old group (48 cases). Under examination [rheumatoid factor (RF), anti-nuclear antibody (ANA), anti-neutrophil antibody (ANCA), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), interleukin-1β (IL-1β), interleukin 6 (IL-6), hemoglobin (HGB), white blood cell count (WBC), human leukocyte antigen-B27 (HLA-B27), complement 3 (C3), etc.], concurrent in terms of symptoms, treatment and prognosis, the ≤26-year-old group was generally lighter than the >26-year-old group; that was, the older the age, the heavier the onset of inflammation and other symptoms, the more complications, the worse the treatment effect, and the worse the prognosis, and there were statistical differences academic significance (P<0.05). According to the course of disease, they were divided into ≤19 years group (46 cases) and >19 years group (44 cases). In terms of examination (RF, ANA, ANCA, ESR, CRP, IL-1β, IL-6, HGB, HLA-B27, C3, etc.), complications, treatment and prognosis, the course of disease ≤19 years group was compared with the disease course> 19 years group Overall mild; that was, the longer the course of the disease, the more severe the onset of symptoms such as inflammation, the more complications, the worse the treatment effect, and the worse the prognosis, P<0.05, the difference was statistically significant. After 6 months of outpatient treatment with biological agents, it was found that biological agents could improve some of the patients’ clinical symptoms and delay the further development of the disease. Compared with the non-biological agent treatment group (48 cases), the biological agent group (42 cases) benefited, and the difference was statistically significant (P<0.05). Conclusion: Through retrospective analysis, this article believes that although adult JIA is diagnosed as connective tissue disease, it has special clinical characteristics with the course of the disease and age. Therefore, it should be recommended to give special attention to JIA patients after adulthood, require regular medical treatment in the adult rheumatology department, according to the corresponding connective tissue disease or JIA diagnosis, and standard treatment; at the same time, pay attention to the history of JIA. In the comparison of biological and non-biological treatment, it is proved that biological treatment can effectively improve some of the clinical symptoms of JIA patients after adulthood. Therefore, it is recommended that biological treatment be used as soon as possible if economic conditions permit to delay the development of the disease.