Abstract： Objective To explore the difference of radiological imaging features of delayed encephalopathy after carbon monoxide poisoning (DECMP) and acute carbon monoxide poisoning (ACMP), and the correlation between the imaging findings and clinical prognosis of the disease. Methods The correlation between imaging findings and clinical manifestations and prognosis of 95 patients with moderate and severe acute carbon monoxide poisoning were retrospectively analyzed. In the above 95 cases , there were 62 cases of ACMP and 33 cases of DEACMP. All patients underwent conventional CT, MRI and magnetic resonance diffusion tensor imaging (DTI). Circular regions of interest(ROI) measurement was used for analysis of average diffusion coefficient(ADC) value and fractional anisotropy (FA) value of the MRI and DTI imaging manifestations in different brain regions. Results The main clinical manifestation of moderate acute carbon monoxide poisoning was consciousness disorder and fatigue;Severe poisoning patients showed deep coma as the main clinical manifestations; The most prominent clinical manifestations of DEACMP were mental disorders and neurological impairment in the extrapyramidal system.A total of 95 cases with moderate or severe CO poisoning showed unilateral or bilateral cerebral cortex, bilateral basal ganglia (white ball), cerebral white matter around bilateral ventricles or bilateral centrum semiovale, around bilateral ventricles cerebral white matter around bilateral ventricles and bilateral centrum semiovale, cerebral cortex and subcortical involvement. CT showed normal or low density shadow.MRI showed that the lesion T 1WI presented slightly low or equal signal, T2WI and FLAIR sequences showed equal, a slightly higher or high signal; DWI sequence showed slightly higher or high signal. ADC value and FA value in different brain white matter regions of DEACMP group was significantly lower than those of ACMP group (P<0.05), especially for those around semi oval center and lateral ventricles of the brain white matter (P<0.01);The ADC values increased significantly, FA value decreased significantly in the nerve nucleus (P<0.05), especially for ADC values in globus pallidus (P<0.01). Conclusion DTI can evaluate the brain tissue damage in patients with DEACMP more early and more accurately.