A test on water application uniformity of center pivot system and field experiment of waterfertilizer coupling on alfalfa were conducted at Saiwusu, Inner Mongolia, to evaluate the effect of water and fertilizer coupling on hay yield by center pivot system. The results show that annual water requirement is 469.4mm for alfalfa of fifth years and three harvests every year. Yield and crop water use efficiency decreased by crop, while water consumption increased. No significant differences existed in alfalfa yield between 100%ETc and 80%ETc irrigation level, but 60%ETc level caused an obvious reduction. It can obtain the best combination of yield and crop water use efficiency when using 80%ETc irrigation level for each harvest. Alfalfa applied with 90kg/hm2 phosphatepotassium compound fertilizer for the first crop and 70kg/hm2 urea fertilizer for the second crop has the highest partial factor productivity (PFP). Neither fertilizer application nor waterfertilizer coupling 〖JP3〗has no significant effect on alfalfa yield in the whole growing season. The actual irrigation amounts applied by the end gun are one third larger than that in the other circular area of the system, while the hay yield has no corresponding increase. In order to reduce waste of irrigation water, the end gun should be selected properly in center pivot irrigation system.