Polymer nanoparticles with dendrimer-Ag shell were prepared and their application in catalytic reduction of 4-nitrophenol(4-NP) was investigated.Cross-linked polystyrene(PS) microspheres were prepared through dispersion copolymerization of styrene,acrylic acid and crosslinking monomer 1,2-divinylbenzene.PS microspheres with average size of 450 nm and narrow size distribution were used as support for the immobilization of dendrimer-Ag shell.The polyamidoamine(PAMAM) dendrimer shell was successively grafted onto the surface of PS microspheres through repetitive Michael addition reaction of methyl acrylate(MA) and amidation of the obtained esters with large excess of ethylenediamine(EDA).Silver nanoparticles were formed directly inside the PAMAM shell through reduction with NaBH_4.The resulting PS@PAMAM-Ag nanoparticles were packed in a stainless steel column and used successfully for catalytic reduction of 4-NP.This technique for packing catalytic polymer particles in a column could improve the efficiency of using the metal catalyst and the tedious separation in catalytic reaction. Polymer nanoparticles with dendrimer-Ag shell were prepared and their application in catalytic reduction of 4-nitrophenol (4-NP) was investigated. Cross-linked polystyrene (PS) microspheres were prepared through dispersion copolymerization of styrene, 2- divinylbenzene.PS microspheres with average size of 450 nm and narrow size distribution were used as support for immobilization of dendrimer-Ag shell. The polyamidoamine (PAMAM) dendrimer shell was transferred grafted onto the surface of PS microspheres through repetitive Michael addition reaction of methyl acrylate (MA) and amidation of the obtained esters with large excess of ethylenediamine (EDA). Silver nanoparticles were formed directly inside the PAMAM shell through reduction with NaBH_4. the resulting PS @ PAMAM-Ag nanoparticles were packed in a stainless steel column and used successfully for catalytic reduction of 4-NP. This technique for packing catalytic polymer particles in a column could impr ove the efficiency of using the metal catalyst and the tedious separation in catalytic reaction.