The invention discloses a method for preparing nanosheet cluster-structure cupric sulfide from a titanium-copper amorphous alloy. The cupric sulfide powder prepared by the method has the advantages of large specific area and high photocatalytic activity. The method comprises the following steps: putting a titanium-copper amorphous alloy strip (comprising 30-70 atm% of Ti and 30-70 atm% of Cu) and a sulfuric acid water solution with the molar concentration of 10-15M into a closed vessel to react at 60-120 DEG C for 24-96 hours, flushing the sample prepared by reaction with deionized water, and drying in a 50-DEG C drying box to obtain the nanosheet cluster cupric sulfide powder. The synthesis method has the advantages of simple manufacturing process and low raw material cost, and is simple, feasible and economical.