The invention discloses an automatic feeding and blanking mechanism for a lens grinder. The automatic feeding and blanking mechanism comprises a lifting module, an overturning module, a feeding frame, a blanking frame, a processing platform and a moving working table. The lifting module comprises a fixed seat, an up-down cylinder, a guide support and a fixed block. The guide support is vertically arranged on the fixed block, the fixed block is fixed at the lower end of the guide support, a cylinder body of the up-down cylinder is fixed on the fixed seat, and a piston rod of the up-down cylinder is connected to the fixed block. The automatic feeding and blanking mechanism is reasonable in structural design, automatic feeding and blanking motions can be achieved rapidly through the matching between the lifting module, the overturning module and the moving working table, an automatic mode is adopted to replace a manual mode, and the automatic feeding and blanking mechanism has motion flexibility, is convenient to operate, easy to control, high in efficiency and quick in speed and greatly improves production efficiency and product pass rate.