Background: Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumors in adults. LncRNA SBF2-AS1 has been reported to promote malignant progression in multiple human cancers. However, the roles and underlying mechanisms of SBF2-AS1 in GBM are still unknown.Methods: The levels of SBF-AS1 were identified in GBM tissues and normal brain tissues, and in GBM cell lines and normal human astrocytes. The effect of SBF2-AS1 on proliferation, invasion and radiosensitivity was evaluated by CCK-8 assay, transwell assay, γ-H2AX foci assay and clonogenic survival assay in vitro and in vivo. The interactions among SBF2-AS1, miR-338-3p and MAP4K3 were validated through luciferase report, RNA immunoprecipitation and western blot assays. Results: In the present study, we comfirmed that SBF2-AS1 was highly upregulated in GBM tissues and cell lines, and its levels were markedly higher in WHO stage III-IV gliomas compared with WHO stage I-II gliomas. Kaplan-Meier survival analysis revealed that glioma patients with high SBF2-AS1 expression had shorter overall survival than those with low SBF2-AS1 expression. SBF2-AS1 inhibition suppressed the proliferation of GBM cells by down-reguating of Ki-67 and CyclinD1. Moreover, silencing SBF2-AS1 increased the proportion of cells in G1 phase and decreased the proportion of cells in S phase. In addition, SBF2-AS1 inhibition suppressed the invasion of GBM cells by down-reguating of MMP2 and MMP9. Xenograft tumor models revealed that the silencing of SBF2-AS1 inhibited tumor growth in vivo. Moreover, the silencing of SBF2-AS1 significantly sensitized GBM cells to radiation in vitro and in vivo. Indeed, we observed a persistence of γ-H2AX staining after ionizing radiation, leading to enhanced DNA repair and radioresistance. Mechanistically, SBF2-AS1 inhibition reduced the expression of MAP4K3 by directly binding with miR-338-3p in GBM cells. Conclusions: Our study demonstrated that SBF2-AS1 enhanced cell proliferation, invaison and radioresistance via modulating miR-338-3p/MAP4K3 axis, and it is an attractive therapeutic target to overcome radioresistance of GBM.