Abstract: After different agricultural practices were used in soybean field, the population of soil microbes and fungal flora structure were tested in different growth period. The result showed that using organic manures or straw returning can increase the population of bacteria and actinomyces, decrease the population of soil fungi; Using chemical fertilizer only can increase the population of soil fungi; Under the same condition of using chemical fertilizer, no-tillage and deep-tillage are not good for reproduction of soil microbe; Continuous cropping can worsen the ecosystem of soil microbes.