The invention relates to a method of removing ionic liquid in a water body by activated carbon adsorption promoted by utilization of phosphates, and belongs to the field of water pollution control. The method includes adding the phosphates into the water body containing the ionic liquid, fully mixing, dissolving, adsorbing the ionic liquid in the water body by using activated carbon, after adsorption balance or adsorption saturation is achieved, eluting the ionic liquid by using an acid eluant firstly, and adjusting the pH of the activated carbon to be slightly alkaline again by using an alkaline solution so that the activated carbon can be reutilized in the next time of adsorption. Compared with the prior art, the ionic liquid removing capability of the activated carbon by adsorption is significantly improved by utilization of the phosphates. The method is free of extra operation and treatment, the adsorption removing effect for the ionic liquid is greatly improved, the activated carbon can be reutilized for a plurality of times, and the method has a good popularization and application prospect.