Objective The in vitro studies of indicators in burn patients with complicated infection have been little studied till now.So this study aims to investigate the change of proliferation of CD64 +neutrophils from the peripheral blood of burn patients in vitro. Methods CD64+neutrophils from peripheral blood of healthy people were isolated and purified, which was followed by stim-ulating its proliferation with inactivated Staphylococcus in vitro.We further analyzed the proliferation index with Modfit 2 analysis soft-ware.86 burn patients were divided into two groups, 44 cases with complicated infection assigned to experimental group, 42 uninfected assigned to controls.We further detect the counts of WBC and the percentage of CD64 +neutrophils, and then analyzed the specificity and sensitivity by using the receiver operating characteristic ( ROC) curves. Results This in vitro study, the average proliferation index of CD64 +cells in experimental wells was significantly higher than controls (6.48 ±0.11 vs 2.63 ±0.02), the difference was statistically significant (P<0.05);the percentage of CD64 +cells in the peripheral blood of patients in experimental group(64.25 ± 13.11%) was significantly higher than patients without infection(16.33 ±2.77%);The sensitivity and specificity of diagnostic meth-od of CD64 +cells for the burn infection were respectively 94.2%and 76.8%, which was superior to the traditional diagnostic meth-od of WBC ( 68.5%, 64.7%) according to ROC curves. Conclusion CD64 + cells in peripheral blood of burn patients complicated by infection increased more significantly and earlier when compared with the traditional diagnostic method, which may be used as a useful diagnostic indicator for burns complicated infection.