The invention discloses a method for preparing nanometer Cu(OH)2/AP composite particles. Ammonium perchlorate and copper salt precursor are ultrasonically dispersed in a nonsolvent of ammonium perchlorate (AP), an alkaline solution is added, and an ultrasonic assisted-chemical liquid deposition method is adopted, so as to obtain the Cu(OH)2/AP composite particles. The ultrasonic assisted-chemical liquid deposition method is adopted to prepare the Cu(OH)2/AP composite particle in one step, the preparation process is simple and fast, and can be used for large batch production, the whole reaction process only needs ultrasonic assistance, the reaction time is greatly shortened, and the safety and the reliability are great. The prepared nanometer Cu(OH)2/AP composite particles are good in dispersivity, nanometer Cu(OH)2 can be relatively uniformly dispersed on the surface of the ammonium perchlorate particle, the agglomeration of the nanometer Cu(OH)2 particles can be prevented, and the catalytic effect can be effectively played.