Objective To investigate the immunotherapeutic effect and mechanism of dendritic cell (DC) vaccine assisted by Tiaohengfang polysaccharides (ThPP) in S180 tumor-bearing mice. Methods Mouse bone marrow-derived cells were cultured in vitro and mature DCs were obtained with the assistance of cytokines and ThPP. The expression of CD80 and CD86 of DCs induced by ThPP was examined, and S180 tumor cells were used as antigens to stimulate dendritic cells to become dendritic cell tumor vaccine. Tumor-bearing models were established in mice by S180 tumor cells inoculated into the armpit of the left forelimb, and the mice were randomly divided into four groups according to body mass, namely tumor-bearing blank group, positive control group (cyclophosphamide), dendritic cell vaccine group adjuvanted by ThPP and TNF-α. The tumor-bearing mice were treated on the 5th and 10th days after inoculation of tumor cells. The tumor-bearing mice were killed on the 12th day and the tumor inhibition was observed by the tumor mass detection. At the same time, peritoneal macrophages were isolated and cultured, and the expression of CD11b and IL-12 were measured by immunohistochemistry. The levels of serum IL-12 and TNF-α in the mice were detected by ELISA. The survival time of the other four groups of tumor-bearing mice was observed after treatment with the same method. Results The expression of CD80 and CD86 in the TNF-α group and ThPP group were higher than those in the blank control group, and the ThPP group was more significant. The tumor inhibition rate and survival extension period of ThPP, TNF-α and positive groups were significantly higher than those of the model blank group. The levels of serum IL-12 and TNF-α in the ThPP group were higher than those in the positive cyclophosphamide group and model black group. There was no significant difference between the ThPP group and TNF-α group. The expression of CD11b in the macrophages of ThPP group was lower than that in the model blank group and positive group, while the expression of IL-12 in the macrophages of ThPP group was higher than that in the model blank group and positive group, without significant difference compared with TNF-α group. Conclusion ThPP-adjuvanted DC tumor vaccine can inhibit tumor growth and prolong survival time of S180 tumor-bearing mice, which is related to promoting the maturation of DCs and increasing the secretion of IL-12 and TNF-α.