A method of preparing the dendritic cell tumor vaccine includes steps as follows. A tumor specimen is primarily isolated and cultured to obtain a plurality of tumor cells. Cancer stem cells having a specific cell surface marker are sorted from the tumor cells. The cancer stem cells are irradiated with a radiation. A plurality of dendritic cells are provided. The dendritic cells and the cancer stem cells irradiated with the radiation are co-cultured for activating the dendritic cells into cancer-stem-cell-antigen-presenting dendritic cells to obtain the dendritic cell tumor vaccine. The dendritic cell tumor vaccine is a mixture of the cancer-stem-cell-antigen-presenting dendritic cells and the cancer stem cells.
