Objective To analyze the imaging findings of MRI and CT of diffuse astrocytoma and to summarize the diagnostic value. Methods The clinical data of 36 patients with diffuse astrocytoma confirmed by operation and pathology in our hospital from June 2011 to May 2015 were retrospectively analyzed. The findings and characteristics of CT and MRI were analyzed and compared with pathology. The combined diagnostic value of MRI and CT was evaluated. Results Pathological grading showed that there were 13 cases of grade II, 12 cases of grade III and 8 cases of grade Ⅳ. The maximum diameter of the lesions was 2.1-8.2cm, (4.5±0.2) cm in average. 2 cases of lesions were infratentorial ones and 34 cases were supratentorial ones. Most of the lesions were in frontal lobe and temporal lobe. There were visible lesions with unclear boundaries and diffuse abnormal signals in most of them; There was no edema around 19 cases and no significant mass effect. Only 12 cases were with mild to moderate cerebral edema and 5 cases were with lateral ventricle compression and midline structure translocation. T1WI sequence showed low signal and T2WI sequence showed high signal. CT scan showed that there were tumors with fuzzy boundaries and low density lesions. 17 cases had no obvious enhancement and 15 cases showed moderate enhancement, with visible nodules, small patchy or irregular ring enhancement. Conclusion Diffuse astrocytoma is common in young people. The imaging findings were particular. To adopt MRI and CT combined examination can achieve scan the multidimensional and multiangle imaging scan. It is helpful for the differential diagnosis.