Ag/SBA-15 nanocomposite was prepared by supercritical fluid deposition (SCFD) method, with AgNO₃ as the precursor and ethanol or glycol as the cosolvent. AgNO₃ was firstly deposited onto the SBA-15 support at 50℃, 23-25MPa, and reacted for 3-24h. The resultant composite was then subjected to calcination and reduction treatment for obtaining Ag/SBA-15 nanocomposite. Characterizations with XRD and TEM show that Ag nanoparticles (with sizes of 3-7nm) or nanowires (5-9nm in width and tens of nanometers to several micrometers in length) are formed in the nanochannels of SBA-15 support. It is demonstrated that SCFD is a green and effective method for preparation of nanocomposite. With the aid of cosolvent, the supercritical carbon dioxide can dissolve the inorganic metallic salts. Moreover, the morphologies of the nanocomposite can be controlled to some extent by selecting the deposition conditions. A catalytic test on the Ag/SBA-15 nanocomposite shows that the sample has a moderate activity, with the complete conversion of CO at 300℃.