Abstract: In view of the problems of long time of modifying and updating and high cost existed in harmonic monitoring systems of coal mine grid which take hardware as core, the paper proposed a design scheme of harmonic monitoring system of coal mine grid based on virtual instrument which takes software as core. It analyzed working principle and hardware structure of the system, introduced implementation of harmonic measurement method based on wavelet transform and FFT transform in details, and gave software design of the system. The simulation result showed that the system can meet with demands of harmonic monitoring of modern coal mine grid well.