Objective To evaluate the influence of Circle of Willis on intravascular hypothermia. Methods A patient-specific model of the Circle of Willis was constructed based on the CT images and the in vitro perfusion experiment with cold water for 20 ℃ was performed. The water was injected from right intracarotid artery (ICA) to the area of middle cerebral artery (MCA) at the flow rate of 30 mL/min and made the cooling period last 15 min. The cooling and rewarming characteristics in the phantom and fluid around MCA were investigated using thermocouples arranged at 27 and 1 spatial locations. The areas distributed with cold water were further visualized using the dyed solution. Results The cold water from right ICA was mainly distributed to right anterior cerebral artery (ACA), MCA, and posterior communicating artery (PCoA), while only a little part of the water could possibly pass through anterior communicating artery (ACoA) to the left ACA. The nearer the locations to the area with cold water, the faster cooling down and also faster temperature recovery rate would be obtained. Moreover, the phantom temperature distributions were asymmetric around MCA due to the complicated bifurcation structures in this area. Conclusions This physical model is useful for investigating the influence of vasculature on endovascular hypothermia and applicable in designing patient-specific hypothermia therapy.