Abstract: OBJECTIVE To study the clinical diagnostic value of common indices for detection of children with acute fever without obvious focus of infections,so as to provide theoretical value for clinical diagnosis.METHODS A total of 456 cases of children’clinical data were selected,who had acute fever but without obvious focus of infections in our hospital from May 2013 to May 2015.Contribution rate of C-reactive protein（CRP）,white blood cell count（WBC）,procalcitonin（PCT）and the neutrophile granulocyte were used for analysis of diagnosis.RESULTS From the 456 children,84cases with serious illness,the PCT and CRP levels were significantly higher than children with non-severe disease（P＜0.01）.CRP diagnostic cut-off point of 67.1mg/L,the sensitivity for the diagnosis of serious disease was 0.810,specificity 0.715;PCT diagnostic cut-off point 0.505μg/L,sensitivity was0.762 and specificity was 0.672.Specificity reached 0.918 when both joint,sensitivity 0.617.A total of 64 patients got infected with the virus and 80 cases of children with bacterial infections,30 cases with mycoplasma infections.According to the different types of infections,CRP among children,PCT,WBC and the percentage of neutrophils were significant different（P＜0.01）.When bacterial and viral infections were identified,the diagnostic cut-off point for CRP was 38 mg/L,the sensitivity was 0.900,specificity 0.813;PCT diagnostic cut-off point0.450μg/L,the sensitivity 0.700,specificity 0.812.If combine the two,the specificity was 0.965,sensitivity0.630.When mycoplasma and bacterial infections were identified,CRP diagnostic cut-off point 80.75mg/L,the sensitivity 0.700,specificity 0.933.CONCLUSION About children with no obvious focus of infections and acute fever,CRP and PCT could help to detect disease severity and etiology for children no more than 5years old,and their combination is more specific.