The hexagonal copper-tin alloy (Cu-Sn) nano-plates were synthesized using a high temperature solvent method, the length of six equilateral edges of hexagonal Cu-Sn nanoplates was 23 nm, and the thickness was 13 nm. The obtained hexagonal Cu-Sn nanoplates were highly monodisperse and allowed the formation of nanoarrays arranged with long-range order. The hexagonal Cu-Sn nanoplates exhibited high catalytic activity on catalytic hydrogenation of 4-nitrophenol to 4-aminophenol. Due to the promotion effect of Sn, the apparent rate constant (k(a)) of hexagonal Cu-Sn nanoplates was three times that of Cu nanoparticles. The density functional theory (DFT) calculations and experimental results demonstrated that Sn could promote the coordination of -NO2 of 4-nitrophenol with Cu-Sn nanoplates and contribute to activation of 4-nitrophenol. In addition, the hexagonal Cu-Sn nanoplates showed high stability and reusability for the reduction reaction, good adaptability in different pH and the ionic strength, and wide applicability for the degradation of methylene blue, methyl orange, and rhodamine B, even in the industrial wastewater, suggesting that the Cu-Sn nanoplates are promising catalysts in organic industry wastewater treatment.