Sulfide precipitation is a favorable method to treat acidic heavy metal polluted wastewater. However, the treatment efficiency is hindered due to the low solubility of metal sulfides, which easily aggregate to form fine particles, thus making it difficult to separate the solid–liquid phases. Herein, crystal seed induction and mechanical strengthening were synergistically introduced to facilitate the growth and aggregation of CuS particles. The generated metal sulfide with the addition of active seeds grew via heterogeneous nucleation on the active seeds and supersaturation of CuS was reduced through mechanical strengthening to accelerate the growth of the particles. Further surface property analysis and the calculated results demonstrated that mechanical strengthening increased the hydrophobicity and aggregation of sulfide particles, which leads to a 5 times higher precipitation efficiency of metal sulfides. This work provides theoretical guidance for the growth and effective precipitation of metal sulfide nanoparticles.