The invention discloses a heat recovery gradient utilization system for an oil-free screw air compressor. The heat recovery gradient utilization system is characterized by comprising an air compressor cooling device, a hot water gradient utilization device and a softened water device; the air compressor cooling device mainly comprises two compression main machines, two safety heat exchangers and a water pump. The hot water gradient utilization device is connected with the air compressor cooling device through a pipe network. The softened water device is connected with the hot water gradient utilization device and the air compressor cooling device through pipelines. By the adoption of the heat recovery gradient utilization system, waste heat of the oil-free screw air compressor can be recovered, required hot water is obtained, and the hot water is utilized in a gradient manner. The invention further discloses a control method for the heat recovery gradient utilization system. Systematic adjustment is carried out according to different water use conditions so as to fully and reasonably use recovered hot water, and recovered heat is efficiently utilized.