The number of patients with malignant tumors has been on the rise worldwide，particularly the developing countries.The immune system，a host defense system，plays a key role in the occurrence and development of tumor and impacts the microenvironment of tumors.According to traditional Chinese medicine，“spleen acts as the guard for the five zang-organs and six fu-organs”，which means the spleen can defend the body through the defense qi.The defense qi serve as a bridge between “spleen acting as the guard for the five zang-organs and six fu-organs” and the immune system.The distribution of the defense qi is closely related to the range of activity，trajectories，and response of immune cells，and the immunological composition，functions，and indicators.As major solutions to tumors，radiotherapy and chemotherapy damage the cellular immune function of patients while killing the tumor cells.Traditional Chinese medicine，which can reduce toxicity and enhance efficacy，serves as one of the adjuvant therapies for radiotherapy and chemotherapy.Therefore，based on “spleen acting as the guard for the five zang-organs and six fu-organs”，this paper explained the influence of traditional Chinese medicine on tumors and the mechanism，laying a theoretical foundation for the prevention and treatment of clinical malignant tumors.