Objective To study the significance of combined detection of procalcitonin ( PCT ) , C-reactive protein( CRP) and lipopolysaccharide( LPS) for early diagnosis of bacterial infection in newborns. Methods Clinical data of ninety-eight newborns from neonatal ward of our hospital were retrospectively studied. Fifty cases with bacterial infectious diseases were selected as infection group,in the same period,48 cases with non-bacterial infectious diseases were selected as control group. In the 24 hours after admission before use of antibiotics,all of cases were picked blood used for testing CRP,PCT,LPS and blood culture, and the results were contrasted and analyzed. Results The levels of serum PCT,CRP and LPS in infection group were respectively significantly higher than those in control group,and the differences were statistically significant(P<0. 05,respectively). In gram-positive bacterium group,the positive rate of combined detection of serum PCT and CRP was obviously higher than that of single detection of PCT or CRP ( 91. 3% vs. 60. 9%,P<0. 05;91. 3% vs. 56. 5%,P<0. 05 respectively) . In gram-negative bacteria group,positive rate of combined detection of serum PCT and LPS was obviously higher than that of single detection of PCT or LPS respectively(88. 9% vs. 59. 3%,P<0. 05;88. 9% vs. 66. 7%,P<0. 05 respectively). Conclusion Joint detection can improve the diagnostic efficiency, and reduce missed diagnosis. And we can identify disease which predominantly infected by positive bacteria or negative bacteria through joint detection,which can contribute to the choice of clinical antibiotic drugs.