Objective To investigate the clinicopathological and molecular pathological features of diffuse hemispheric glioma （DHG）. Methods A total of 27 DHG patients who underwent surgical resection or stereotactic biopsy at the Neurosurgery Department of Beijing Tiantan Hospital Affiliated to Capital Medical University from January 2021 to May 2023 were selected as the study subjects. Clinical data of the patients were collected and followed up. Hematoxylin eosin staining and immunohistochemical staining were used to detect the characteristic protein expression in tumor cells. The next generation sequencing and pyrosequencing methods were used to detect the molecular pathology characteristics of tumors. Results The median age of onset for 27 DHG patients was 22.5 years old； 59.3% （16/27） were males； 24 cases of tumors mainly located in unilateral frontal， parietal， and temporal lobes， with only 3 cases located in bilateral cerebral hemispheres. The histopathological results showed that 5 out of 27 tumors had the morphology of astrocytoma， 17 had the morphology of glioblastoma， 1 had glioblastoma with ganglion like differentiation， and 4 had the morphology of primitive neuroectodermal tumors. The immunohistochemical staining results showed that all 27 cases of tumor glial fibrillary acidic protein staining were diffuse positive， and transcription factor 2 protein expression in oligodendrocytes was negative， α- the expression of X-chromosome related genes in thalassemia/mental retardation syndrome was missing， and p53 protein was expressed with missense or nonsense mutations. Isocitrate dehydrogenase 1 R132H， isocitrate dehydrogenase 2 R172K， H3K27M， and BRAF V600E proteins were all negative. 24 cases of tumor cell nuclei expressed H3.3G34R protein to varying degrees， and 3 cases of tumors diffusely expressed H3.3G34V protein. The Ki67 proliferation index varied from 3%-80%. The molecular pathological results showed that all tumors had H3F3A gene H3.3 G34 （35） mutations， 23 cases with ATRX deletion， and 27 cases with TP53 mutations. Follow up for 2-24 months， of which 5 cases died 10-24 months after diagnosis， with a median progression free survival of 6.5 months and a median total survival of 11 months. 5 cases were lost to follow-up. Conclusions DHG has a high degree of malignancy， and despite the addition of radiotherapy or chemotherapy for total or near total resection lesions， patients still quickly relapse， progress， or die. Therefore， immunohistochemical and molecular pathological testing of DHG is necessary， which is more conducive to active treatment and prognostic evaluation of DHG patients.