To improve the removal efficiency of nickel in the water and obtain a kind of adsorbent with low-cost and high efficiency, peanut shell carbon derived from waste peanut shell was produced and modified by potassium permanganate(KMnO₄) and potassium(KOH). Box-Behnken design and response surface methodology were used to optimize the modification conditions of the carbon. SEM and BET were employed to characterize the morphological and structural changes of the peanut shell carbon before and after the modification. The modified peanut shell carbon before and after Ni(Ⅱ) adsorption was analyzed by FTIR to preliminarily discuss its adsorption mechanism. The results show that the best modification conditions are:temperature 361℃, the mass ratio of KOH to carbon 2.5 and the concentration of KMnO₄ 0.76%. Under these best modification conditions, the maximum adsorption capacity of nickel is 85.02 mg/g, which is 15.6 times higher than that of the carbon without modification, proving its superior adsorption performance and pragmatic value. The results of FTIR show that -OH and -NH₂ are the main functional groups in the Ni(Ⅱ) adsorption process and they participate in the co-precipitation and complexation reactions with Ni(Ⅱ). Besides, the effect of cation-π is also one of the adsorption mechanisms of modified peanut shell carbon to Ni(Ⅱ).