The present invention provides a method of treating high-molybdenum tungsten mineral or tungsten slime by means of three-ion column exchange molybdenum-eliminating technology so as to obtain ammonium paratungstate with high purity at low cost. The treating process includes grinding, alkali leaching, filtering and concentration to obtain sodium tungstate crystal; water dissolving, filtering and sulfurizing sodium tungstate; ion exchange to eliminate molybdenum; desulfurizing sodium tungstate liquid; ion exchange to eliminate impurity and desorbing tungsten with ammonia water and ammonium chloride solution to prepare ammonium tungstate solution; and evaporation to obtain ammonium para-tungstate crystal. The present invention has low cost.