To study the formation process of feldspathic sandstone and sand compound soil in the Mu Us Desert, 1:1, 1:2 and 1:5 ratios of feldspathic sandstone and sand were mixed to obtain compound soil to plant crops, and analyze the rules of changes in water-stable aggregates of the compound soil among the 4 years crops growing process. The results showed, before crop planting, the order of mass percent of > 0.25 mm and 0.25-2.00 mm water-stable aggregates in three kinds of compound soil was 1:1>1:2>1:5, showing that the overall content was low; the mass percent of > 0.25 mm water-stable aggregates remained at 18.38%-28.22%; the mass percent of 0.25-0.50 mm, 0.50-2.00 mm, 2.00-5.00 mm, and > 5.00 mm water-stable aggregates was close with each other in each kind of compound soil. After 4 years of planting, the mass percent of > 0.25 mm water-stable aggregates in 1:2 compound soil increased significantly and exceeded other 2 kinds of compound soil, reached 32.34%; the main components of > 0.25 mm water stable aggregates in 1:1, 1:2, and 1:5 compound soil were 0.25-0.50 mm (53.54%), 0.25-0.50 mm (59.43%), 0.05-2.00 mm (52.16%), aggregates; 0.25-2.00 mm aggregates increased significantly in all three kinds of compound soil, with the highest increase in 1:2 compound soil; the organic matters of 1:2 compound soil were significantly correlated with 0.25-0.50 mm and 0.25-2.00 mm water-stable aggregates. The results showed that the ratio of 0.25-2.00 mm aggregates in the three kinds of compound soil was increased after 4 years of crop planting and 1: 2 compound soil was most favorable for the formation of aggregates.