Objective To study the effects of asymmetrical entry velocity profile on the flow separation in carotid artery sinus. Methods A model of "TF-AHCB" is adopted in an experimental simulation of steady flow recirculation, then flow visualization is realized by dyeing method and velocity profiles of the sections in common carotid artery and in carotid artery sinus are acquired by LDV. Results The results demonstrate that asymmetrical entry velocity profile has an apparent influence on the flow separation in the carotid sinus. The size of the separation zone when the peak of velocity profile deviates outward from the axis about 1/3 of the pipe's radius is as large again as that when the peak of velocity profile deviates inward. Conclusion Effects of asymmetrical entry velocity profile on the flow separation in carotid sinus are so significant that the deviation of the peak of entry velocity profile becomes an important factor influencing the distribution of atherosclerotic plaque.