Citrus is the most productive fruit in the world and China. China is a big country in the production and processing of citrus. With the rapid development of citrus planting and processing industry, the by-product resources such as fruit dropping and residual fruit in the citrus planting process, waste and waste water during the processing process have also increased. Problems such as waste of resources and environmental pollution caused by low utilization of by-product resources are more prominent. At present, in addition to the direct utilization of citrus by-product resources, they were also used to prepare functional ingredients such as pectin, flavonoids, carotenoids, limonoids, essential oils, and synephrine by extraction, or prepare ethanol, citric acid, feed and organic fertilizer by fermentation and conversion of biomass. However, the problems of low comprehensive utilization rate, lack of key technologies and core equipment, and slightly fewer high-value-added functional products were also the current difficulties need to be resolved. Green, low-carbon, high-efficiency, high-value, comprehensive recycling will be the development trend of citrus by-product resource utilization. In response to the existing problems, suggestions on strengthening scientific and technological research, formulating special plans, and strengthening fiscal revenue might effectively improve the utilization of the by-product resources of citrus, hoping to provide a reference for the high-quality development of the comprehensive utilization of citrus by-product resources.