Objective This study focused on the application regularity of medicinal and dietary substances (MDS) of traditional Chinese medicine (TCM) diet therapy during rehabilitation, in order to help patients with Corona Virus Disease 2019 (COVID-19) reduce sequelae and improve their life quality. Methods The official websites of the national and provincial health committees, the website of the National Administration of Traditional Chinese Medicine, the China BioMedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang Database were used to search the keywords, such as “coronavirus” “novel coronavirus pneumonia” “COVID-19” “protocol” “guideline” “consensus” and “rehabilitation period”. The search time was from the establishment of databases to July 31, 2022. The prevention and control protocols of various provinces and cities were manually supplemented and screened out. The information on the frequency, property, flavor, meridian tropism, and efficacy of MDS was collected for association rule analysis through the Apriori algorithm. Hierarchical cluster analysis was performed using the Euclidean distance and longest distance. Results A total of 18 protocols were screened out, including 56 lists of TCM diet therapy, and 47 kinds of MDS with a frequency of 132 times during the rehabilitation of COVID-19. Among them, six lists of diet therapy were collected from national websites, 26 from local government websites, and 24 from social and academic institution websites. The intended population can be divided into seven categories including normal recovery, lung-spleen Qi deficiency, deficiency of both Qi and Yin, spleen-stomach weakness, deficiency of Yang Qi, kidney Qi deficiency, and blood deficiency. Shanyao (Dioscoreae Rhizoma) and Lianzi (Nelumbinis Semen), followed by Dazao (Jujubae Fructus) were used most commonly in MDS, with mainly flat property, sweet flavor, and spleen and lung meridians in meridian tropism. Besides, deficiency-tonifying drugs were commonly used in MDS. Through association rule analysis, 12 groups of association MDS pairs were obtained. The pair of Yiyiren (Coicis Semen) and Chenpi (Citri Reticulatae Pericarpium) had the highest Lift value, and Yiyiren (Coicis Semen) was used most frequently in the MDS category for eliminating pathogenic factors. The results of complex network analysis showed that the core MDS were Yiyiren (Coicis Semen), Shanyao (Dioscoreae Rhizoma), Huangqi (Astragali Radix), Fuling (Poria), and Dazao (Jujubae Fructus). Three core categories were classified by cluster analysis, including the category of strengthening spleen, nourishing kidney, and grasping Qi, the category of removing phlegm, abating panting, and regulating Qi, and the category of strengthening the middle-energizer and reinforcing Qi. Conclusion Based on the TCM theory, most patients during the rehabilitation of COVID-19 are in a state of lingering pathogens due to deficient vital Qi. TCM diet therapy is based on the principle of “giving both reinforcing and reducing treatment”, and the MDS combinations focus on both reinforcing the health Qi and eliminating pathogenic factors. The diet therapy mainly uses the MDS with flat property and sweet flavor, which belongs to deficiency-tonifying drugs, adding suitable MDS of pathogen-eliminating drugs according to different situations. The ultimate goal is to promote lung inflammation absorption, improve pulmonary fibrosis, increase immunity, reduce the occurrence of sequelae, and improve life quality.