The invention aims to provide a method for preparing magnetic nano-composites and removing phenols pollutants in water. The method for preparing the composites comprises the step of preparing the magnetic nano-composites by using iron chloride hexahydrate, ferrous chloride tetrahydrate and carboxymethyl-beta-cyclodextrin polymers as raw materials. The method for removing the phenols pollutants in water comprises the following steps: adding the magnetic nano-composites to an aqueous solution containing the phenols pollutants, regulating the pH of the solution to 5, and oscillating the solution for 4 hours at the room temperature, as a result, the phenols pollutants in the water can be effectively adsorbed and removed. After the adsorption is completed, an adsorbing agent in an external magnetic field is separated and recovered, and finally the magnetic nano-composites which are recovered are desorbed and regenerated to be reused for adsorbing the phenols pollutants. By the method, the phenols pollutants in the water can be effectively removed, the operation is simple, secondary pollution is avoided, and the adsorbing agent is easy to separate and recycle to be reused.