Abstract: The primary composition of citrus rhizosphere microorganisms is bacteria,whose number reaches up to 76871×10⁷ per gram dry soil,nest is fungi with 17549 numbers per gram dry soil,the least is actinomyces,the number is 12462 per gram dry soil.Those quantity are 67.6,12.4 and 26.9 times higher than those in no-root soils in the citrus field,respectively. The rhizosphere effect is very remarkable.Rhizosphere bacteria tends to be more abundant in Citrus ushiu mare soil.Quantity of those rhizosphere microorganisms are influenced by soil physical and chemical characters and changing with citrus variety stock as well as season. There are also close relation between disease enduring and susceptibility of citrus root and root stem to some diseases with the quantity,type and distribution of beneficial and harmful rhizosphere microorganisms.