A pot experiment under the conditions of awning was conducted to clarify the coupling effects of different irrigation and potassium supply on the change of soil organic matter, total nutrient （total nitrogen, total phosphorus, and total potassium）and available nutrients （available nitrogen, available phosphorus, and available potassium）, and accumulation of nutrient by peanut (Arachis hypogaea Linn.), by using the random block design with two factors and four levels for each factor, i.e. W1—35% field capacity, W2—50% field capacity, W3—65% field capacity, W4—80% field capacity, and K0—K2O 0 g/kg soil, K1—K2O 0.15 g/kg soil, K2—K2O 0.30 g/kg soil, K3—K2O 0.45 g/kg soil. Peanut variety ‘Huayu 25’ was the tested materials. The results showed that the absorption of available nitrogen was promoted as the potassium fertilizer amount was increased. Soil available phosphorus in W1K1 and W2K1 treatments increased with the decreasing of soil total phosphorus under water stress. It showed that a small amount of potassium fertilizer helped to the release of phosphorus for the dryland. The fertilizer K1(135 kg/hm2) treatment could promote the increasing of soil available potassium and soil nutrient balance, the concentration of available potassium in K1 was 0.43 to 0.59 times more than that in the initial soil, and increased with the increasing potassium fertilizer amount. The accumulation of nutrients (N, P and K) by peanut showed a rising trend with increasing irrigation amount when the potassium fertilizer amount was the same. N uptake increased firstly and then decreased with increasing irrigation amount, but only under the condition of water stress. Except the adequate moisture treatment (W4), the accumulation of P by peanut increased firstly and then decreased with increasing K application in other water treatment. No matter how the water supply was changed, K accumulation showed a parabolic pattern with the increase of potassium supply, and all the maximal values appeared in the mild potassium (K2) treatment. The correlation between peanut nutrient accumulation and total biomass yield, and pod yield were significant or extremely significant, there was also a significant positive correlation between total biomass and pod yield. Based on the comprehensive consideration of sustainable soil nutrient supply, the accumulation of nutrient by peanut and the formation of yield, it was recommended to maintained the moisture at 65% FC, and to control the amount of potassium fertilizer (K2O) at 135 kg/hm2 to 270 kg/hm2.