The present application discloses a single-point diamond dresser for a grinding wheel based on acoustic emission online monitoring, which includes a support module, an anti-interference module, a compression cooling module and an acoustic emission online monitoring module. An acoustic emission sensor monitors the dressing state of the grinding wheel online; a damping sheet and a damping interlayer greatly reduce external noise interference; a high pressure coolant causes an upward elastic deformation of an elastic spacer and the damping sheet, enlarging a contact force between the acoustic emission sensor and the core and moreover improving a sensitivity of the acoustic emission sensor; the coolant flows through the coolant passages in the core to cool a dressing area; current limiting passages, pressure relief cavities and perforated pressure-relief plates limit flow and reduce a pressure of the coolant, reducing the interference of the coolant on the grinding wheel dressing.