Abstract: Influence of reaction conditions on the size and distribution of colloidal silver particles was investigated.With PVP and sodium hexametapnosphate as stabilizing agents,silver colloids of different average sizes and size distributions were prepared by wet chemical reduction of AgNO_3 with NaH_2PO_4,by changing the reaction temperature,the AgNO_3 concentration and the feeding rate of AgNO_3 solution.The size and distribution of the silver particles were determined by laser diffraction,UV-vis spectroscopy and TEM.Silver particles of small size and narrow distribution were obtained when the AgNO_3 solution was mixed immediately with the reducer.The reaction temperature and AgNO_3 concentration have complicated effects on the size distribution because of their influence on the coalescence and growth of the particles.