Abstract: OBJECTIVE To study the changes of serum PCT,TNF-α and acute phase reactants of patients with infection in ICU and its relationship with the prognosis,in order to provide references for the prevention,control and treatment of patients with infection in ICU. METHODS A total of 34 patients with infection in ICU from Jul. 2014 to Apr. 2016 were selected as observation group,and 34 patients without infection in ICU at the same time were selected as control group. The serum PCT,TNF-α and acute phase reactants of the two groups were compared, the detection results of the two groups with the survivors and the dead were compared too, and the detection results of different infection sites and pathogenic bacteria infection situation of the two groups were compared. RESULTS The serum PCT,TNF-α and acute phase reactants of observation group were all higher than those of control group,and the levels of the survivors and the dead of observation group were all significantly higher than those of control group (P＜0.05). CONCLUSION The serum PCT,TNF-α and acute phase reactants expression levels of patients with infection in ICU are relatively higher,and the expression levels have active clinical value for the prognosis of patients.