For the purpose of exploring the influence mechanism of Fenlong tillage on the physicochemical properties and microbial number of sweet sorghum soil，the sweet sorghum field in Helan Mountain farm and pranch in Yinchuan，Ningxia was taken as the experiment area.Four farming modes，including traditional (CK)，Fenlong 30 cm (F30)，Fenlong 50 cm (F50)and deep tillage 40 cm (DT40)were set up，so as to study the change rule of physical properties，available nutrient content and microorganism quantity in sweet sorghum soil in different tillage modes，and the soil quality in different tillage modes was comprehensively analyzed.The results showed that :(1)Compared with CK and DT40，F30 and F50 modes can better coordinate three-phase ratio of soil，significantly reduce soil bulk density，increase soil water content and soil porosity，and effectively improve the physical properties of soil surface layer.(2)Compared with CK，F30，F50 and DT40 can significantly increase available nutrient content in three soil layers of 0～15，15～30 and 30～45 cm.However，CK treatment was only significantly different from F30 and F50 treatments(P<0.05):the content of alkali-hydrolyzated nitrogen increased by 5.3%～14.5%，13.1%～15.9% and 3.2%～4.1%，respectively；the content of available potassium increased by 13.0%～19.1%，15.7%～20.2% and 2.8%～6.7%，respectively；and the content of available phosphorus increased by 5.2%～21.1%，5.7%～23.3% and 0.8%～5.0%，respectively.(3)Compared with CK，F30，F50 and DT40 can significantly increase number of microorganisms in three soil layers of 0～15，15～30 and 30～45 cm.However，CK treatment was only significantly different from F30 and F50 treatments(P<0.05):the number of bacteria increased by 6.3%～118.7%，18.8%～111.1%，9.4%～30.0%，respectively；the number of fungi increased by 40%，33.3%～100.0%，20%，respectively；and actinomycetes number increased by 7.0%～40.0%，23.9%～86.7%，4.4%～26.7%，respectively.Based on the synthetic analysis of principal components，the soil quality of sweet sorghum ecosystem in Fenlong tillage mode was higher than CK and DT40 treatments，and the yield of sweet sorghum was significantly increased in Fenlong tillage mode，among which F30 tillage mode was more extensively used in production.