A novel silica monolith modified with Ag/Au nanoparticles was prepared for the on-column surface enhanced Raman spectroscopy (SERS). The bare monolithic silica column was prepared from in-situ co-condensation of tetraethoxysilane (TMOS) and methyl trimethoxysilane (MTMS) in the presence of polyethylene glycol (PEG) via a sol-gel process in the capillary, and was chemically modified with (3-mercaptopropyl) trimethoxysilane (MTPMS), followed by immobilization of Ag/Au nanoparticles. Transmission electron microscopy (TEM) and UV-Vis spectrometer were used to collect the TEM images and the extinction spectra of the nanoparticles colloid, respectively. Scanning electron microscope (SEM) was utilized to record the morphology of the silica monolith. The authros used p-aminothiophenol (PATP) as a probing molecule, and the SERS effect was investigated on Au/Ag nanoparticle-modified silica monolith under the excitation line of 633 and 532 nm, respectively. It is concluded that nanoparticle-modified silica monoliths will have broad application to the on-site detection of food and water contaminants in the field.