Food is a multi-component， multi-phase change， multi-scale complex of microstructures， so the processing of food will also involve multiple scales of physical， chemical， biological properties and other changes. For this complex process， only the traditional macro-scale analysis problem will ignore the specific impact of mesoscale and micro-scale changes， and it is difficult to accurately explain the mechanism. However， it is difficult to predict the changes of mesoscopic and macroscopical characteristics of food only by studying the microscopical characteristics of food. The application of the multi-scale method in food processing is conducive to better restoring the changes in the microscopic characteristics of the processing process， clarifying the internal mechanism， and revealing the essential causes of the internal changes in food. In recent years， with the rise of new technologies and the improvement of methods， the research on mesoscopic and microscopic scales has become more and more in-depth. Scholars have also begun to pay more attention to the changes in physical properties during processing， and explore the specific changes in food processing with the combination of multi-scale ideas. Some studies also combine numerical simulation methods， which can predict and intuitively display the characteristics of various kinds of food after processing. From the perspective of different food processing fields， this paper introduces the methods and technologies to solve the problems in different scales in food processing， such as freeze-thaw， drying and emulsification.