Cancer is the second leading cause of death around the world. Cancer may be induced by viral infection (EBV,HBV and HPV), bacterial infection (Helicobacter pylori), carcinogen, ultraviolet (UV) radiation exposure, and genetic mutation. Tumor can be suppressed by traditional surgery, radiotherapy, and/or chemotherapy with devastating side effects and very poor quality of postoperative life. The therapeutic index has been further promoted by the newly developed nanomedicine. However, the disseminated tumor cells can result in micrometastases. So the cancer can just be supresssed but not cured by these ways. Fortunately, the developments of immunology have successfully improved many disciplines with special effort on oncology. Various immune cells including B cells, T-lymphocytes (TL), natural killer(NK) cells, dendritic cells (DCs), macrophages, and polymorphonuclear leukocytes are recruited to the tumor. These immune cells can recognize, eliminate, and protect the body from viral, bacterial infections, and the transformed cells(pre-cancer cell) extension. The modification of host immune system, and/or the utilization of components of the immune system for cancer treatment are called immunotherapy. The immunotherapy is not only to target and kill tumor cells in aspecific manner, but also to alert the immune system to eradicate the disseminated tumor cells present in the blood circulation and micro-metastases in remote organs. Herein, the development of immunology, cancer immunotherapy,tumor immuno escape was introduced firstly. Then the correlations between host, the tumor and the nano particulates were proposed. And how to improve the cancer immunotherapy by finely nanocarrier's engineering (nanoimmunotherapy) was systematically illustrated with special focus on the unique pathology of tumor microenviroments and properties of immuno cells.