In this paper，a field experiment combined with laboratory analysis were used to study the characteristics of soil microbial community distribution in yam field compared with that in grain field，and the improvement effects of alfalfa，clover and soybean intercropping with yam on soil microecological environment.The results showed that the numbers of soil bacteria，fungi and actinomycetes in yam field and grain field both decreased with the deepening of soil layer in 0～100 cm.The numbers of soil bacteria and fungi in yam seedling stage were higher than those in grain field，especially the number of fungi，which was enhanced by 1.86～4.48 times.Nevertheless，the numbers of nitrogen-fixing bacteria and actinomycetes in grain field were higher than those in yam soil，with magnitudes being 1.51 and 0.75 times higher in 0～20 soil layer，respectively.At harvest，the numbers of bacteria，nitrogen-fixing bacteria and actinomycetes in 0～20 and 20～40 cm soil layers of yam field were lower than those in grain field，while the number of fungi was higher，and the ratio of bacteria to fungi in 0～100 cm soil layer was also decreased.Intercropping yam with alfalfa，clover and soybean could significantly increase the numbers of soil nitrogen-fixing bacteria，phosphate-solubilizing bacteria and actinomycetes in 0～40 cm soil layer.The results indicated that continuous cropping of yam could significantly affect the composition and structure of soil microbial communities，and intercropping legumes had been helpful for the remediation of soil microecological environment.