The invention relates to a feeding device of a grinding machine. The feeding device comprises a hopper and a controller; a conveying belt is arranged at the bottom of the hopper, a belt wheel is connected with the conveying belt, a storage box is arranged at the bottom of the conveying belt, grinding materials are stored in the storage box, a fixed plate is mounted at the bottom of the storage box, an air cylinder is mounted on the fixed plate, and the air cylinder is connected with a push plate; the storage box is connected with a sliding plate, the sliding plate is connected with a conveying device, a side plate is arranged on the conveying device, an electric motor A is mounted on the lower portion of the conveying device, a feeding groove is formed in the conveying device, and an approach switch and a backflow-prevention device are arranged on the conveying device; the controller is provided with a communication unit, and the communication unit is connected with a computer. The feeding device has the beneficial effects of being reasonable in design, simple in structure, low in production cost, convenient to operate, automatic in feeding, time-saving, labor-saving, high in work efficiency, stable in conveying, safe, reliable, long in service life, high in practical performance, capable of improving production efficiency and wide in application range.