The present disclosure provides an internal cooling/external cooling-switching milling minimum-quantity-lubrication intelligent nozzle system and method, relating to the field of milling lubrication. The system includes: a vision system, configured to acquire a real-time milling depth of a workpiece and send the real-time milling depth to a lubrication manner controller for processing; a lubrication system, including an internal cooling system and an external cooling system connected together to a cutting fluid supply source through a reversing device; and the lubrication manner controller, configured to communicate with the vision system and the lubrication system respectively, and control the reversing device to act according to a set milling depth threshold and data acquired by the vision system, so as to adjust and switch to the internal cooling system or the external cooling system to work. Milling depth data of a machine tool is collected, the milling depth data is transmitted to a control center for data analysis and processing, the data is compared with an initially set internal cooling/external cooling switching threshold to obtain the most suitable cooling and lubrication manner under current machining conditions of the machine tool, and the control center controls the internal cooling and external cooling systems according to the obtained result to realize intelligent switching of the cooling and lubrication manner between internal cooling and external cooling.