The present invention falls within the field of geological disaster prevention. Provided are a system and method for monitoring the seepage rate and moisture content of a rock-soil body based on an IHAT-FBG. The system comprises a power supply, a power supply current control heating system, an IHAT-FBG, an FBG demodulation device and a data analysis and processing system which are connected in sequence. The method comprises the steps of: packaging an alundum tube into an IHAT-FBG, and burying same into a rock-soil body after calibration; actively heating the FBG by means of an internal heating technology, and using an FBG demodulation device to record a wavelength change; and using data processing and analysis software to calculate a temperature characteristic value of the FBG, and substituting the temperature characteristic value into a linear function: ΔTt = a - bv and w = kΔTt + c determined by means of calibration experiments, so as to calculate the seepage rate and moisture content of the rock-soil bod
