Mesoporous KIT-6 supported highly dispersed silver nanoparticles and nano-networks were successfully synthesized in supercritical carbon dioxide and co-solvent solution using AgNO3 as precursor, followed by calcinations. The nanocomposites were characterized by XRD, TEM, ICP and N2 adsorption-desorption isotherms. Three kinds of co-solvent were investigated including ethanol, the mixture of ethanol and ethylene glycol as well as the mixture of ethanol and water. It was found that when only ethanol was used as co-solvent, a small amount of AgNO3 was deposited onto the complex nanochannels of KIT-6 even if the deposition time was 12h. However, it took a short deposition time of 1h to deposit a large amount of precursors onto the substrates when the mixture of ethanol and ethylene glycol as well as the mixture of ethanol and water were used as co-solvent. The large solubility of AgNO3 in ethylene glycol or water had a positive effect on the dissolution of precursor in scCO2, which was beneficial to the adsorption of precursor on the substrates.