Abstract: The role of sodium humate on Escherichia coli was investigated to provide potential novel antibacterial drugs for treating disease which caused by enteropathogenic bacteria.Antimicrobial activity for sodium humate on Escherichia coli was determined using dilution plate counting method.Ultrastructure of sodium humate against Escherichia coli was observed under transmission electron microscope.The results showed that adding sodium humate （5%，10%，15%） decreased the number of Escherichia coli （P＜0.05）.The more obvious inhibition effect （P＜0.05） as the level of sodium humate content increased.Different strains in the same processing conditions，with the extension of time，the more obvious inhibitory effect.Observation under transmission electron microscope was carried out that adding 5% sodium humate and adding 5% sodium humate with pH regulating changed the permeability of cell membrane, made cell excrescent and inhibited cell division. The results provided a theoretical basis to further understand sterilization mechanism of sodium humate.

Key words: sodium humate; bacteriostatic action; Escherichia coli; transmission electron microscope