Radiation dermatitis (RD) caused by radiation therapy has brought pain to patients. Therefore, we aim to investigate the efficacy of preventive external application of Traditional Chinese medicine (TCM) gel in conjunction with psychological care for the prevention of RD in patients with malignant tumors. A total of 130 patients who underwent radiotherapy in our hospital from January 2021 to December 2022 were selected as the research objects. The patients were divided into two groups based on their nursing modes: the conventional group received TCM gel treatment for Radiation Therapy Oncology Group (RTOG) grade II skin damage, while the combination group received preventive external application of TCM gel before radiotherapy along with psychological care support. The incidence of RD, quality of life, negative emotional changes, and satisfaction with nursing care were recorded and compared between the two groups. Our results demonstrated a significant reduction in the incidence of RTOG grade III–IV skin damage, an obvious improvement in patient’s quality of life and negative emotions, and a higher satisfaction in the combination group compared to the conventional group (P < 0.05). In conclusion, this study suggests that the preventive external application of traditional Chinese medicine combined with psychological care during radiotherapy holds significant potential in preventing RD in patients with malignant tumors. Furthermore, it is proposed that the observed efficacy of the Chinese medicine gel in preventing radiation dermatitis may be attributed to its anti-inflammatory properties, primarily mediated by key active ingredients such as berberine and obacunone.