Abstract: To improve the precision, automation, and intelligence level of the gear grinding process with the microcrystalline corundum grinding wheel, online monitoring of the grinding status and wear mechanism of the grinding wheel was carried out. The intrinsic correlation between grinding force time-frequency two domain signals and the contact status of the grinding wheel and workpiece, the wear degree of the grinding wheel was established. A new online monitoring method based on real-time force signals for the grinding state of the grinding wheel was proposed. Meanwhile, the wear mechanism underlying the morphology of microcrystalline corundum grinding wheels was characterized and analyzed using laser confocal microscopy and scanning electron microscopy. Research has shown that the distribution pattern of waveform characteristic indicators such as kurtosis, waveform index, peak index, and pulse index in the time-domain spectrum of grinding force shows a distinct trend of varying cutting depth grinding state≥steady-state grinding state of significantly worn grinding wheel≥steady-state grinding state of lightly worn grinding wheel>non-contact state. However, the variation of the waveform characteristic values of the grinding force amplitude spectrum under different grinding states is completely opposite to that of the time-domain signal. The three-dimensional roughness of the working surface of the grinding wheel shows a slight decrease and then a rapid increase with the evolution of wear. The polycrystalline structure of the microcrystalline corundum abrasive particles gives it the ability to update and sharpen along the microcrystalline interface, showing layer-by-layer cleavage peeling.