Monitoring chemical reaction processes is of great significance in the study of the reaction mechanisms, and the optimization or control of reaction conditions. In this work, we demonstrate a novel monitoring method of chemical reactions using fiber SERS probes. The high-performance fiber SERS probes are prepared by the laser-induced evaporation self-assembly method (LIESAM), where lots of Au-nanorod clusters are deposited on the fiber facet for providing large SERS enhancement factor and good hot electron catalytic property. The remote and in-situ monitoring of chemical reactions is achieved through simply dipping the probes into the reaction solution. Taking the classic reduction reaction from 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP) by sodium borohydride (NaBH