By revealing the THz spectral characteristics of glioma and contralateral normal brain tissue, and analyzing the spectral differences in tumor space, this study provides theoretical support for non-invasive tumor diagnosis. Using an orthotopic U87 glioma cell tumor-bearing mouse model, terahertz spectroscopy is employed to characterize the absorption properties of the glioma lesion area and the contralateral brain tissue. Single-factor Analysis Of Variance (ANOVA) and Tukey's Honestly Significant Difference (HSD) post hoc test are adopted to assess the significant differences in spectral absorption between different layers of the tumor. Immunofluorescence results show differences in cell proliferation ability and vascular density in the glioma lesion area. THz spectral analysis indicates that above 2 THz, the absorption coefficient of the tumor area is significantly higher than that of normal brain tissue, especially with the peripheral surrounding area (L(6-7)) having a higher absorption coefficient than the tumor enhancement area (L(1-2)). ANOVA analysis confirms that the spectral absorption differences between different layers of the tumor are statistically significant (p<0.05), and Tukey's HSD test further confirms the specific differences between each layer within the tumor. Homogeneity of variance test shows significant heterogeneity within the tumor layers, while the normal brain tissue area exhibits more consistent spectral characteristics. The study demonstrates that terahertz spectroscopy can effectively identify the internal heterogeneity of glioma, especially the absorption differences between the lesion center and the infiltration area, providing important evidence for noninvasive tumor diagnosis and showcasing its application potential.