This study looked at the inhibitory effects of Apocynum venetum tea flavonoids extract (AVTFE) on mouse glioma G422 cells. Through the use of high performance liquid chromatography, the flavonoids in AVTFE were examined (HPLC). Meanwhile, mice were injected with glioma G422 cells to create a mouse model of a transplanted tumor. AVTFE might significantly (P < 0.05) lower serum sIL-2R content and raise serum IFN-γ content in tumor-bearing mice, according to an analysis of mouse serum. In addition to reducing the rise in spleen weight and spleen index in mice brought on by transplanted tumors, AVTFE can limit the development of transplanted tumors in G422 cell mice. AVTFE can also boost immunity by encouraging T and B lymphocyte proliferation in tumor-bearing animals. AVTFE was therefore verified to have immunomodulatory properties and to limit the proliferation of glioma G422 cells.