Objective To analyze the imaging manifestations of central nervous system leukemia and the diagnostic efficiency of CT and MRI. Methods A total of 40 cases of patients with central nervous system leukemia (CNSL) treated in our hospital from July 2016 to July 2017 were selected for the study and treated with CT and MRI plain scan and contrast enhanced scan. The imaging manifestations were analyzed, and the lesions sites and the signal characteristics were mainly observed, and the CNS infiltration sites were compared between different types of leukemia patients. And the sensitivity, specificity and accuracy of CNSL by CT and MRI diagnosis were analyzed by taking the examination results of cerebrospinal fluid (CSF) as the gold standard. Results In this group of patients. ①there were 3 cases of leptomeningeal leukemic infiltration, and the disappearance of sulcus and brain cistern and the stripy low density lesions were seen in the CT, and the low signal in T1WI, high signal in T2WI/FLAIR, gyrus swelling, slightly high and then significantly enhanced signal in the DWI were shown in the MRI. ②there were 6 cases of brain parenchyma infiltration with multiple tumors, and the low signal in T1WI, high signal in T2WI/FLAIR and high signal in DWI, with no obvious occupying effect, enhanced enhancement and 3 cases complicated with hemorrhage were shown by MRI. ③ there were19 cases of dural involvement involving the forehead barrier, and the soft tissue density lesions were seen in the CT, and the soft tissue signal lesions significantly enhanced after enhancement were seen in the MRI. The remaining 12 cases were mixed type of above types, including soft meninges infiltration, parenchymal infiltration, dural involvement, and the short/equal T1WI signal and short/long T2WI signal were seen in the mixed lesions. There was no significant difference in the infiltration sites between different types of leukemia (P>0.05). The specificity and accuracy of CNSL by MRI diagnosis were higher than those by CT diagnosis (83.33% vs.16.67% and 87.50% vs.67.50% ) (P<0.05), but the sensitivity was not statistically significant by the two methods (76.47% vs 88.24%) (P>0.05). Conclusion The imaging manifestations of CT and MRI in central nervous system leukemia have a certain characteristics, especially MRI enhanced examination can help improve diagnostic efficiency and is worthy of clinical promotion and application.