The invention belongs to the technical field of lithium ion battery positive electrode materials and in particular discloses a method for preparing a multi-element precursor with low impurity content. According to the method disclosed by the invention, impurities contained in the multi-element precursor are separated, and the method comprises the following steps: simultaneously adding a ternary mixed metal salt solution of inorganic salts or organic salts of nickel salts, cobalt salts and manganese/aluminum salts, a precipitator and a complexing agent into a reactor, stirring, and performing coprecipitation so as to obtain precursor suspension B; guiding the suspension and a mother solution into an electromagnetic separation tank, stirring, establishing magnetic fields in different directions, respectively constraining residual positive ions and negative ions, dissociating so as to obtain precursor suspension D in which impurity ions are removed; and filtering, drying, screening, removing the magnetic powder, thereby obtaining the multi-element precursor product. The process disclosed by the invention is simple, high-efficiency, low in cost, low in pollution, energy-saving and environmentally friendly, and the prepared multi-element precursor product is low in impurity content, meets the positive electrode material requirements of lithium ion batteries and is suitable for large-scale industrial production.