Abstract: Cutting time is one of the key factors affecting the yield and quality of alfalfa. In these experiments, we evaluated the effects of different cutting times in 2009 and 2010 on the yield and quality of alfalfa hay. The hay yield and crude protein yield of alfalfa were highest at the early flowering stage (P<0.001). Cutting before the early flowering stage resulted in significantly decreased hay yield and crude protein yield (P=0.003). As the interval between the first and second cutting times increased, the contents of neutral detergent fiber, acid detergent fiber, and crude fiber increased (P<0.001), and the crude protein content decreased (P<0.001). With the first cutting at early flowering, an interval of 72 days (2009) and 68 days (2010) resulted in the highest yield and crude protein production (2275.2 kg/ha and 180.2 kg/ha, respectively, in 2009; 2063.6 kg/ha and 263.1 kg/ha, respectively, in 2010). These results indicate that the appropriate time for the first cutting of alfalfa on the Loess Plateau is at the early flowering stage in mid-June, and that of the second cutting is approximately 70 days later in late August.