This paper focuses on microwave research and measurements for agricultural and food processing applications. Normally, microwave devices and components are used as a moisture detector for soil, agricultural, and food products. For instance, the moisture content in fruits normally is correlated with the maturity and sweetness of the fruits. In addition, the moisture content can be used to determine the storage period and the quality of the agricultural products after processing by an industrial factory. In this chapter, several microwave applications of agri-food products are selected to be reviewed comprehensively, such as microwave heating mechanism for several agri-food products, heating/drying, or freeze-drying process in food industry to control pathogenic and spoilage microorganisms in packaged foods, moisture soil testing, fruit moisture measurement, ripeness/storage period determination, fruit sweetness …