The objective of this study was to determine the effect of zero tillage on soil microorganismas and biological activity.The field expetiment was conducted on a sandy loam soil,Which had been cultivated for many years,in Yangzhou,Jiangsu Province.After 6 years of the adoption of Zero tillage on the soil (wheat and rice rotation) 0-28 cm soils were sampled to determine microflora and biological activity so as to make a comparison between zero tillage (ZT) and conventional tillage (CT).