To investigate the changing characteristics of soil nutrients in tomato protected cultivation, enhance the fertilization management for protected vegetables, and promote the sustainable development of protected agriculture, the plow layer in the cultivated areas of tomato protected cultivation was selected as the research object. Soil physical and chemical properties were measured by conventional detection methods to analyze nutrient changes. The results showed that in the study areas of tomato protected cultivation, the pH of the soil and the content of water-soluble salts increased. The content of organic matter was above the medium level, and the contents of available nutrients such as nitrogen, phosphorus and potassium were abundant. The soil was in a state of secondary salinization and excessive nutrient enrichment. In addition, the contents of trace elements were uneven across the soil. In the subsequent planting process, it was recommended to increase the application of organic fertilizers to raise the content of soil organic matter, improve the soil structure, and promote microbial activities. Meanwhile, attention should be given to the combined application of fertilizers containing secondary and micronutrients along with those containing macronutrients to balance the nutrients supply of soil, and increase overall productivity.