The effects of aluminum sulfate and organic materials on the composition and complex of organic carbon in saline-alkali soil were studied by laboratory culture experiments and adding different gradient organic materials (10,20,30,40,50,60 t/hm²) and the same amount of aluminum sulfate (0.2 t/hm²). The results showed that the organic carbon content and active organic carbon content could be significantly increased by applying aluminum sulfate and organic materials. When aluminum sulfate was applied and the amount of organic materials was 30 t/hm², the growth trend of microbial carbon began to slow down, the soil microbial quotient reached the peak, and the Kos value was the lowest compared with other treatments. The application of aluminum sulfate and organic materials can promote the aggregation of soil particles from small to large, and at the same time increase the content of organic carbon in the composite body of each particle. When the application amount of organic materials is 30 t/hm², the soil structure can be obviously changed. In other words, when aluminum sulfate is applied and the amount of organic materials is 30 t/hm², the soil fertility and soil structure of saline-alkali soil can be improved effectively, and the saline-alkali soil can be improved economically and reasonably.