In this study,a silver colloid as surface enhanced Rarman scattering(SERS) substrate was rapidly synthesized via one step method.The biological fingerprint spectra of 18 groups of Raman characteristic peaks were thereafter obtained from the detection of opportunistic pathogen Stenotrophomonas maltophilia by SERS.Results demonstrated that the minimum concentration of bacterial suspension could reach 5×106 colony forming units(CFU)/mL with the relative standard deviations(RSDs) for repeatability detection of 6.8%-16%,which could meet the basic requirements for qualitative analysis in biomedical field.Besides,the Raman signals of pathogenic bacterial cells in the blood of positive patients obtained by this method are close to those of pure cultured strains,further indicating that this method is rapid(10 min),facile,portable and low cost,and has a broad application prospect in clinical diagnosis.