The integration of plasmonic nanostructures with portable fiber Raman spectrometer shows great potential in real time detection of remote liquid samples and in-vivo species. In this system, the surface enhanced Raman scattering (SERS) active noble metal nanostructures are required to bind on the fiber surface to generate stable SERS signals toward the target species. Herein we show that by using thiol-terminated silane couple agent (3-mercaptopropyl trimethoxysilane) which can be decorated on the silica surface of fiber probe, SERS-active Au nanospheres and Au nanocubes can be stably assembled on the fiber surface through the readily formed Au-S and Ag-S covalent bond. The resultant SERS fiber probes demonstrate high signal reproducibility (relative standard deviation lower than 3%) and can be sensitive to 10^-8 M methyl parathion, showing potentials in SERS-based online and portable detection of liquid samples.