Objective To analyze the changes of hematological parameters and coagulatory function in sever fever with thrombocytopenia syndrome (SFTS) in Zhoushan island.Methods Automated blood analyzer and automatic coagulation analyzer were used to measure hematological parameters and coagulatory function in SFTS patients before and after ten days treatment.Results The counts of white blood cells (WBC),neutrophils and lymphocytes and platelets of the 27 cases with SFTS were significantly lower than those of normal controls (P ＜ 0.05) ; Moreover,the counts of platelets was significantly higher in the cases who recovered as compared with those who died (P ＜ 0.05).Prothrombin time (PT),activated partial thromboplastin time (APTT) and thrombin time (TT) of SFTS patients before treatment were longer than normal controls,whereas fibrinogen (FIB) was lower (P ＜ 0.05).Pearson correlation analysis showed that APTT and platelet (PLT) of SFTS patients before treatment had significantly negative correlation (P ＜ 0.05),as well as PT,APTT and TT were negatively correlated with PLT of SFTS patients with 10 d treatment.Conclusion Paying close attention to the hematological parameters and coagulation function,especially PLT and APTT,has important clinical significance in diagnosis and monitoring of disease progression in patients with SFTS.