Abstract: Alfalfa (Medicago sativa) plant yield and nutrient change characteristics of forage crop rotation were studied in a long-term experiment in the gully region of the Loess Plateau. The one-year Medicago yield was 8 763 kg/ha (the lowest) and the three-year Medicago yield was 12 020 kg/ha (the highest) but the four-year yield fell to 9 665 kg/ha. The N, P, K uptake (218, 11, 105 kg/ha respectively) in one-year Medicago was the lowest. The P, K uptake of three-year Medicago was the highest (23 kg/ha and 185 kg/ha respectively) and compared with one-year Medicago, the P uptake was 109.1％ higher and the K uptake was 76.2％ higher. The N uptake of four-year Medicago was the highest, about 351 kg/ha, which was 61％ higher than one-year Medicago. Soil organic matter, total nitrogen and alkali solution nitrogen content increased each year, organic matter increased form 15.60 to 18.26 g/kg, total nitrogen increased from 1.20 to 1.50 g/kg, and alkali solution nitrogen increased from 64.74 to 88.02 mg/kg. However, soil total phosphorus, available phosphorus and potassium declined each year. Total phosphorus fell from 0.86 to 0.76 g/kg, available phosphorus fell from 14.00 to 9.27 mg/kg, rapidly-available potassium fell from 70.51 to 54.35 mg/kg. Consequently, the optimum amount of potash in production fertilizer is needed to meet the needs of high quality and high production of afalfa.