This paper describes a simulation of microwave brain imaging for the detection of hemorrhagic stroke. Firstly, in the research process, the formula of DebyeⅡwas used to study tissues of brain and blood clot so that microwave frequency band was confirmed for imaging. Then a model with electromagnetic characteristics of brain was built on this basis. In addition, an ultra-wideband (UWB) Vivaldi antenna is designed to use for transmitting and receiving microwave signals of widths 1.7 GHz to 4 GHz. Microwave signals were transmitted and received when the antenna revolved around the brain model. Symmetric position de-noising method was used to eliminate the strong background noise signals, and finally confocal imaging method was applied to get brain imaging. Blood clot was distinguished clearly from result of imaging and position error was less than 1 cm.