With the technology development of cold atmospheric plasma (CAP), CAP draws more and more attentions to the biological application due to the low gas temperature and high activity of reactive species produced by CAP. Plasma medicine was also established as an innovative interdisciplinary, combining with the plasma physics, chemistry, life sciences and clinical medicine, etc. Here, we gave a brief introduction about CAP, its generation and composition, the interaction with liquid and tissues, and some of the major applications in biomedical field, such as sterilization, blood coagulation, wound healing, skin disease and dental treatment. In addition, we focused on the application of CAP in cancer treatment. CAP can effectively induce tumor cell death, inhibit cell proliferation and migration, induce differentiation of tumor cells and suppress the potential of stem cells, and can increase the sensitivity to chemotherapy. These beneficial effects shows a promising prospects for CAP application in tumor therapy.