Wet sieving of red soil aggregates with biogas slurry and fertilizer mixture as dispersive medium is conducted to explore the response mechanism of the stability of dryland farming red soil aggregates to biogas slurry and fertilizer mixture and to provide theoretical basis for popularizing rational agricultural use of biogas slurry.This experiment consists of seven treatments:CF1(100% chemical N)；CF2(80% chemical N+20% biogas slurry N)；CF3(60% chemical N+40% biogas slurry N)；CF4(40% chemical N+60% biogas slurry N)；CF5(20% chemical N+80% biogas slurry N)；F(100% biogas slurry N)；CK(pure water).The total N，P and K of each mixture are equal，and the N-P2O5-K2O is 120-90-135 kg·hm-2.The soil >0.25 mm water stable aggregate content(WR0.25)，aggregate average mass diameter(MWD)，geometric average diameter(GMD)，aggregate stability(AR)and fractal dimension(D)were analyzed.From CF1 treatment to CK treatment，WR0.25，MWD，GMD and AR show an upward trend，while D shows a downward trend.In each treatment，the content of water stable aggregate < 0.25 mm is the highest(30.9%～33.9%).The content of WR0.25 in each treatment is significantly lower than that of >0.25 mm mechanical aggregate(DR0.25)in the tested soil samples.With the increase of the biogas slurry in mixed solution，WR0.25，MWD，GMD and AR all show an upward trend，while D shows a downward trend.Aqueous solution and ions have an impact on soil aggregates，and the destruction of soil aggregates is mainly manifested as the destruction of large aggregates and the formation of small aggregates，while organic macromolecules can weaken the dispersion of aggregates.The water stability of soil aggregates increases with the increase of organic matter in the mixed solution.