Abstract: In experimental farm of Inner Mongolia University for Nationalities from March to July in 2009, using five-year Asparagus officinalis L. cv.Apollo as experimental material, we studied the effects of different amount of potassium fertilizer on yield and nutrient quality of green asparagus. The results are as the following: the yield of green asparagus and the weight of per branches of green asparagus is the first increase after decreasing trend with the increase of the amount of potassium fertilizer when the amount of potassium fertilizer is within 0-375kg hm-2. And the yield and the weight of per branches is the highest when the amount of potassium fertilizer is respectively 300 kg hm-2 and 225 kg hm-2; the number of green asparagus goes up with the increase of the amount of potassium fertilizer. The content of soluble protein at each stage is gradually increased with the increase of the amount of potassium fertilizer. The content of soluble sugar in the early and middle increase first and then decrease of which the highest is the amount of potassium fertilizer of 225 kg hm-2 in the early , is the amount of potassium fertilizer of 330 kg hm-2 in the middle, gradually increase in the late. The content of crude protein goes up with the increase of the amount of potassium fertilizer and other nutritional content have no obvious change. Ca, Mg elements gradually decreased with increasing potassium fertilizer and other mineral elements with no obvious relation of potassium fertilizer. Under this experimental condition, the combination of yield and nutrient quality, the amount of potassium fertilizer of 300 kg hm-2 is appropriate for green asparagus.