The invention relates to a preparation method for a methanol synthesizing catalyst and belongs to the technical field of catalyst preparation. The preparation method comprises the steps of: first, preparing a mixed solution of zinc nitrate and aluminum nitrate and an alkaline precipitator solution, adding the alkaline precipitator solution into the mixed solution till the pH is 7, and then washing, drying and roasting the mixed solution to obtain a ZnO-Al2O3 carrier; then preparing an ammonia water solution and a reducing agent solution of copper sulfate, dispersing the ZnO-Al2O3 carrier in a sodium hydroxide solution, at a reaction temperature, simultaneously adding the ammonia water solution and the reducing agent solution of the copper salt into the sodium hydroxide solution containing the carrier, continuously stirring the solution, and continuously stirring the solution after addition; and finally, washing, drying, roasting and moulding a solid obtained by solid-liquid separation to obtain the copper, zinc and aluminum catalyst. The copper, zinc and aluminum catalyst prepared by the preparation method has the advantages that the active ingredient Cu is small in grain size and high in dispersity. Compared with a catalyst prepared by virtue of a traditional coprecipitation method or a step-by-step precipitation method, the methanol yield is high and the thermal stability is good.