Metal cutting fluid, made of complex chemical ingredients, mainly plays an important role in cooling, lubrication, rustprevention and cleaning during machining process. There are hundreds kinds of metal cutting fluid with different functions that can meet the engineers’ needs under different processing conditions. According to the characteristics of many kinds of cutting fluids, many components and low content, it was pointed out that there were shortcomings in the use of cutting fluid, such as short storage time, high storage requirements, high transportation cost and expensive disposal cost of waste liquid.The online mixing technology based on microlubrication was proposed, that was, the cutting fluid was used in the process according to the change of the processing object and the processing precision, and the components were mixed according to the formula, readytouse, and precision supply. The main problems those needed to be solved in the analysis of online mixing were multicomponent online mixing of cutting fluid, precise control of microflow, uniform mixing under pulsating conditions and mixing uniformity of multicomponent microflow. Online mixing based on microlubrication solves the problems of cutting fluid in metal processing, improves the effective utilization of cutting fluid and environmental protection. It has important theoretical value and practical application value.