As a stable substance in soil organic matter, soil humus can not only change the physical and chemical properties of soil, such as soil fertility, air permeability, and adsorption, but also affect the number of microorganisms in the soil. Soil humus is an important indicator of soil fertility. The freeze–thaw effect is widely distributed in north and northeast China. Under the effect of alternate freeze–thaw cycles, a series of changes in the content of soil humus occur. In this study, humus-related components, such as humus carbon (HE), humic acid (HA), fulvic acid (FA), and humin (HM), were studied. The effect of freeze–thaw cycles on the soil fertility of saline wetland was investigated. Our paper provides data for the evaluation of the soil nutrient status in saline wetland. In response to the environmental policy of controlling soil desertification, people should improve the control technology of soil desertification in saline wetland and implement sustainable development strategies.