The invention relates to a transformer operation auxiliary monitoring system and method based on a disaster prevention and reduction system of a power grid. The system comprises an on-site data collection module, a data analysis transmission module, and a disaster prevention and reduction background module, wherein the on-site data collection module, the data analysis transmission module and the disaster prevention and reduction background module are connected with each other. The on-site data collection module comprises a disaster warning information monitoring unit, a micrometeorological monitoring unit, a transformer sound collection unit, and a water immersion monitoring unit, wherein the micrometeorological monitoring unit, the transformer sound collection unit and the water immersion monitoring unit are connected with the disaster warning information monitoring unit. The data analysis transmission module comprises a sound signal filtering unit, an abnormal judgment unit, and a signal transmission unit, wherein the sound signal filtering unit comprises a frequency domain energy detector. The disaster prevention and reduction background module comprises a signal enhancing unit. The system and method can reduce the data size, and improve the recognition precision.