Abstract: Objective To explore the clinical diagnostic value of time to positivity (TTP) in blood culture for the coagulase-negative Staphylococci (CoNS) blood infection in adults. Methods A retrospective analysis on data of 142 isolated CoNS strains in blood culture in hospitalized adult cases in Chinese PLA General Hospital from August 2014 to December 2015 was done. TTP was compared between bloodstream infection group and contamination group. Receiver operator characteristic curve (ROC) was used to analyze the clinical diagnostic value of TTP for CoNS blood infection in adult blood culture. Results TTP in infection group and contamination group were (24.82±9.46) h vs (42.71±19.11) h, respectively (P < 0.01).ROC curve showed that TTP=24.90 h was the optimal cut-off point to differentiate bloodstream infection and contamination, with the area under the curve (AUC) of 0.810(95%CI: 0.740- 0.880)， sensitivity of 64.1% and specificity of 87.2%. Conclusion TTP possesses a certain reference to the diagnosis of adult CoNS blood infection, which can be used as an auxiliary diagnosis marker.