Objective To evaluated the diagnostic value of malignant biliary obstrutive disease magnetic resonance cholangiopancreatography(MRCP).Methods 21 cases with malignant biliary obstructive disease diagnosed by clinic and CT were examined by MRCP,the results of MRCP and operation-pathology were analysed.Results The accuracy of MRCP for evaluating the cause of obstructive were 90.5%(19/21),dilated biliary duct appeared "soft canes-like"and "sausage-like",obstructive ends of biliary duct exhibited "cut-off form","down cup mouth-form"and "mouse tail-form".Conclusion Malignant biliary obstruction can accurately diagnosed by MRCP,it may provide an efficient method for the patients who can not accept ERCP provide an efficient alternative to direct cholangiopancreatography.