Coolant is usually used to reduce the temperature of machine component cutting in order to ensure the quality of parts and extend the tool life. An automatic cooling supply system was designed, which was composed of three parts, such as the control module that controlled the flow rate of coolant changing with the cutting temperature, the control module for liquid level in coolant tank and the control module for coolant recycling. Through temperature sensor and liquid level sensor, the collected data was sent to the singlechip microcomputer to control the flow rate of the coolant and complete the automatic supply of coolant. The system can realize the automation of coolant supply process, and achieve the goal of energy saving and environmental protection, reducing the production cost. It has a good application value.