The conversion of land uses was frequent in the saline-alkali reclamation region of the Yellow River Delta (YRD), China. However, the knowledge of the combined effects of carbon (C), nitrogen (N), and phosphorus (P) stoichiometry for soil and enzyme under different land use patterns is limited. We investigated soil C, N, P stoichiometry and soil extracellular enzyme activities of three representative land use patterns (Alfalfa artificial grassland, AG; wheat-maize rotation field, WM; native grassland, PC). The results showed that the average soil stoichiometry of AG, WM, and PC was 31.32: 1.74: 1, 34.05: 1.46: 1, and 26.58: 1.14: 1 respectively, indicating that the level of C and N in the YRD was low. The AG was beneficial to promote the mineralization of C, N, and P, but its effect on the sequestration of C and P was not as good as WM. The average enzyme stoichiometry of AG, WM, and PC was 0.96: 0.76: 1, 0.94: 0.74: 1, and 0.86: 0.73: 1 respectively, which deviated from 1: 1: 1, and were significantly correlated with soil stoichiometry, indicating that enzyme stoichiometry in the YRD was nutrient dependent rather than homeostasis. Meanwhile, according to the vector analysis of enzyme stoichiometry, PC could alleviate C limitation of soil microorganisms. Collectively, land use changes affected C, N, P stoichiometry, and should further change the biochemical cycle and microbial nutrient limitation. Therefore, we argued that conversion and proper conduct of land should be cautions for the degraded land restoration and ecological security, and develop perennial legume forage and conservation tillage for crops should be taken for soil healthy and sustainable development.