Abstract：In order to investigate the effects of Montmorillonite （MM） on Cu， bacterial community and lettuce growth in contaminated soil， pot experiments with different Cu concentrations （100， 200， 400 mg·kg-1） and five addition levels （0， 2%， 4%， 6% and 8% W/W） were established. The results showed that when soil Cu concentrations were 100， 200 and 400 mg·kg-1， 6%MM， 8%MM and 8%MM promoted the growth of lettuce， and the Cu contents in lettuce were the lowest. Compared with CK100， CK200 and CK400， Cu contents in lettuce decreased by 18.1%， 12.8% and 11.5%， respectively. Suitable MM significantly reduced the available forms of Cu in soil. MM can change the composition and structure of soil bacterial community， such as Sphingomonas， Streptomyces， Bacillus and so on. The results of RDA analysis showed that Sphingomonas， Bacillus and Streptomyces could reduce the accumulation of Cu in plants by regulating soil pH， Cu morphology and NH4+-N content， thus so as to accelerate plant growth under stress. The results of this study can provide theoretical support for the remediation of different degrees of soil Cu pollution.