The invention provides a processing method of hawthorn thick broad-bean sauce. The processing method comprises the following steps: finely selecting hawthorns, soybeans and castanea mollissima, steaming the soybean, pulping the hawthorns, drying and grinding the castanea mollissima, inoculating aspergillus oryzae to raw castanea mollissima powder and steamed soybeans, and making koji; mixing the fermented soybeans, hawthorn pulp and cooked castanea mollissima powder, adding a certain amount of seasonings, adding water, filling tanks, fermenting, and sterilizing to prepare the hawthorn thick broad-bean sauce. The hawthorn thick broad-bean sauce provided by the invention does not contain xanthan gum or any other food thickening agents, and has the characteristics of nature, greenness and nutrition and the like compared with traditional thick broad-bean sauce, has the advantages of good appearance and taste, thick uniform textures, sauce smell, hawthorn smell, dark brown color, luster, mellow taste, no peculiar smell, and thick textures, is suitable for popular taste, and can meet the demand on higher food quality due to the improvement of life levels of people; through pH detection, total acid, amino nitrogen and other indexes conform to the national standard.