Aim To investigate the effect of nanobacteria on the injury of human umbilical vein endothelial cell (HUVEC) and the secretion of superoxide dismutase (SOD). Methods HUVECs were treated with the different concentration nanobacteria, and the cell viability was tested by methyl thiazolyl tetrazolium (MTT) analysis. HUVECs were attacked with a concentration of 0.5 Mcfarland of nanobacteria. The lactate dehydrogenase (LDH), malondialdehyde (MDA) and SOD levels were detected in the supernatant of culture medium at 0,6, 2,4, 48 and 72 h, respectively. Results Compared with the control group, the cell viabilities were significantly decreased by treatment with nanobacteria (the absorbance values were 0.1,0.005 and 0.02) for 48 and 72 h (P＜0.05). Compared with the control group, the concentrations of LDH and SOD in cell culture solution were significantly increased in nanobacteria treatment group (P＜0.05), while the content of MDA was not significantly changed (P＞0.05). Conclusion Nanobacteria can injure HUVEC, and increase the activity of SOD in HUVEC.