Inclusion Criteria:  Meet hemophagocytic lymphohistiocytosis (HLH)-04 diagnostic criteria; patients were diagnosed with autoimmune disease associated HLH (Macrophage activation syndrome, MAS). No HLH induction therapy was performed. The expected survival time is more than 1 month. Serum creatinine ≤ 1.5 times normal；Serum human immunodeficiency virus(HIV) antigen or antibody negative； Hepatitis C virus (HCV) antibody is negative, or HCV antibody is positive, but HCV RNA is negative；HBV copies less than 1E+03 copies/ml. Total bilirubin ≤10 times the upper limit of normal; serum creatinine ≤1.5 times the normal value The left ventricular ejection fraction (LVEF) was normal. No uncontrollable infection. Contraception for both male or female. Informed consent obtained.  Exclusion Criteria:  Pregnancy or lactating Women； Allergic to ruxolitinib； Active bleeding of the internal organs； uncontrollable infection； Serious mental illness; Non-melanoma skin cancer history; Patients unable to comply during the trial and/or follow-up phase; Participate in other clinical research at the same time.