Based on the data of soil major nutrient content and parallel observation of grass yield in the Sunite desert grassland in central Inner Mongolia from 2005 to 2024, the paper used mathematical statistical methods such as M-K mutation test and principal component analysis, to conduct a comprehensive analysis of the major soil nutrients in the Sunite desert grassland. The results showed that the interannual variation of the major nutrients in the soil of the Sunite desert grassland was not significant, manifested as an insignificant decrease in organic matter and total potassium content, and a weak upward trend in total nitrogen and total phosphorus content; as the soil depth increased, the organic matter and total potassium content showed a weak downward trend, the total nitrogen content showed a “low-high-low” trend, and the total phosphorus content showed a “high-low-high” trend; the total nutrients in the soil had undergone sudden changes in the time series; an evaluation was conducted on the major nutrients in the soil of the Sunite desert grassland. The soil showed a deficiency in organic matter content (level 4), a significant deficiency in total nitrogen and phosphorus content (level 5), and an abundance of total potassium content (level 1); the cumulative variance contribution rate of the first and second principal components reached 81.62%; the organic matter, total phosphorus, and total potassium had higher loadings in the first principal component, while the total nitrogen had higher loadings in the second principal component; the grass yield showed a non-significant negative correlation with total nitrogen, a significant positive correlation with total phosphorus, an extremely significant positive correlation with total potassium, and a non-significant positive correlation with organic matter. In short, soil nutrients play a crucial role in grassland ecosystems, affecting the growth, development and yield of grass. Studying the characteristics and impacts of soil nutrients changes in grassland provides a scientific basis for the rational utilization of local grassland resources and effective protection and restoration of the ecological environment.