Conversion of nitroarenes to aminoarenes has attracted great attention in pharmaceutical industry, agricultural production, environmental protection and chemical catalysis area. In this work, ficin capped gold nanoclusters(ficin@AuNCs) were prepared for the reduction of 4-nitrophenol to 4-aminophenol. The proposed catalyst was characterized by transmission electron microscopy, dynamic light scattering, fluorescence spectra and UV-Vis spectra. With NaBH4 as the reducing agent, the reduction reaction could carry out completely within 10 min at 25 °C. Interestingly, the resultant catalyst exhibited size-related properties in the reduction, smaller ficin@AuNCs exhibited higher catalytic activity. Its present pseudo-first-order rate constant was found to be 2.95×10−3 s−1 and the catalytic activation energy was 27.7 kJ/mol. Moreover, ficin@AuNCs-based catalyst displayed good stability, heading to 4-nitrophenol conversion of 98.5%―100.0% after six consecutive cycles. It has shown a great potential in construction of unique catalysts based on AuNCs for reduction reaction.