Abstract: Objective To investigate the efficacy and safety of compound cantharidis capsule combined with pemetrexed and platinum-based drugs in the treatment of elderly patients with advanced lungadenocarcinoma. Methods A total of 80 patients with advanced lung adenocarcinoma were retrospectively selected as the study subjects. According to the treatment regimen, they were divided into chemotherapy group (treated with pemetrexed and platinum-based drugs) and traditional Chinese medicine combined with chemotherapy group (treated with compound cantharidis capsule combined withpemetrexed and platinum-based drugs), with 40 cases in each group. The short-term efficacy, serum tumor markercarcinoembryonic antigen (CEA), carbohydrate antigen 72-4 (CA72-4), carbohydrate antigen 125 (CA125)levels, and the incidence of adverse reactions were observed and compared between the two groups. The patients were followed up, and the progression-free survival (PFS) and overall survival (OS) of the two groups were recorded. Results The objective response rate (ORR) and disease control rate (DCR) in the traditional Chinese medicine combined with chemotherapy group were higher than those in the chemotherapy group, with statistically significant differences (P < 0.05). After treatment, the serum CEA, CA72-4 and CA125 levels in both groups were lower than those before treatment, and the levels in the traditional Chinese medicine combined with chemotherapy group were lower than those in the chemotherapy group, with statistically significant differences (P < 0.05). There was no statistically significant difference in the incidence of grade 3 to 4 adverse reactions between the two groups (P>0.05). The progression-free survival rate and overall survival rate in the traditional Chinese medicine combined with chemotherapy group were higher than those in the chemotherapy group, with statistically significant differences (P < 0.05). Conclusion Compound cantharidis capsule combined with pemetrexed and platinum-based drugs can significantly improve the ORR and DCR, reduce serum tumor marker levels, prolong the survival of patients with advanced lung adenocarcinoma, and has good safety.