The bio-sensing for rapid detection of bacteria based on surface-enhanced Raman scattering (SERS) has been widely explored for recent years.It is still a challenge to achieve a high sensitive,reproducible label free detection method for bacteria.In this work,a label-free SERS detection method of E.coli based on growing in silver colloid was reported.Optimized growing conditions including shaking speed,time and temperature was used to help construct a rapid SERS method.It was found that the enhancement of the Raman signal of E.coli could be achieved to 1.8×104cps with high reproducibility.Three strains of E.coli DSM 1116/498/5695 could be successfully discriminated using such SERS method combining discriminant analysis.Finally,the lowest concentration of E.coli at1×105 cells/mL can be detected by SERS mapping.Thus,our detection method offers higher sensitivity and reproducibility compared to previously reported label free methods,opening an avenue for developing various SERS-based biosensors.