In this paper, silver nanoparticles (Ag NPs) were successfully prepared in situ by chemical pulp fiber (CPF) without any additional reductants. In the green synthesis of Ag NPs, CPF acted as both a weak reductant and a stable carrier. The effect of different synthesis conditions was investigated, and the Ag NP load rate was up to 28.12 wt%. The size of the Ag NPs followed a standard Gaussian distribution, ranging from 10 to 50 nm, and a face-centered cubic structure was identified by XRD and TEM. In addition, the AgNPs/CPF composites exhibited good thermostability below 280 degrees C according to TG analysis. Owing to the high load rate and large specific surface area of Ag NPs, AgNPs/CPF composites exhibited excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The conversion rate was up to 95.91% after recycling 50 times, and the catalyst was easily separated from the reaction system. Based on the advantages of high conversion rate, excellent catalytic activity and reusability, AgNPs/CPF composites hold tremendous potential in eliminating nitrophenol and its derivatives from industrial pollution.