[Objective] The soil enzyme activities in different artificial forage in the Loess Plateau was researched in order to provide a scientific basis for improving the stability of artificial vegetation and soil fertility on the Loess forage.[Methods] Seven grasslands planted 3 years including Poa crymophila, Elymus nutans, Uraria crinite, Elytrigia intermedia, Medicago sativa, Astragalus adsurgens, Onobrychis viciaefolia, were selected as the research objects. Soil samples were taken from 0-5 cm and 5-10 cm soil layers in March, June, September and December, to investigate the activity of urease, sucrose enzyme, alkaline phosphatase and catalase.[Results] The activity of urease, sucrose enzyme, alkaline phosphatase in 0-5 cm layer was higher than that in 5-10 cm layer, but there was no significant difference in the activities of catalase between the two soil layers. The activity of urease, sucrose enzyme, and alkaline phosphatase in June was higher than that in March, September and December, but the activity of catalase was not significant different. The activity of soil enzyme in M. sativa was the highest, while the lowest in A. adsurgens. The interaction of soil depth and season had a significant effect on the activities of four enzymes(p<0.01). Herbage variety and season showed significant interaction on the activity of the urease, sucrose enzyme and phosphatase.[Conclusion] The soil enzyme activities of different grasslands in the Loess Plateau changed seasonally, and planting artificial forage could effectively improve soil enzyme activities and soil fertility conditions.