Abstract: Microcrystalline cellulose (MCC) was used as raw materials and loaded with CuO nanoparticles (CuO NPs). Then, 3-chloropropyltrimethoxysilane (CPTES) and diethanolamine (DEA) were added for grafting reaction to prepare CuO NPs@MCC–Si–N(OH)₂. CuO NPs@MCC–Si–N(OH)₂ was characterized with FTIR, XRD, thermal gravimetric analysis and morphology analysis. The results show that CuO NPs can be successfully loaded on the surface of MCC, and silane coupling agent can improve the dispersion of the composite and the ability to graft amine groups, thus enhancing its catalytic activity, and increasing the redox reaction efficiency of sodium borohydride (NaBH₄) and methylene blue (MB). Hence, MB stain is degraded rapidly. It’s also found that CuO NPs@MCC–Si–N(OH)₂ with 20wt% DEA shows the best catalytic effect, and the highest removal efficiency is 99.71% after treating 30 mL MB solution (3 mmol/L) with 30 mg CuO NPs@MCC–Si–N(OH)₂ and 10 mg NaBH₄ within 5 min, and the removal rate is 93.24% after five cycles.