Personalized ventilation (PV) has the ability to improve inhaled air quality and accommodate the individual thermal preference. In this paper one kind of personalized ventilation system which supplies fresh air at the microphone position is investigated numerically. A numerical thermal manikin with the real geometry of human body is used to study the airflows around the occupant equipped with PV. The performance of one RNG k-ε model and the standard k-ε model is compared. The benefits of PV under different uniform room ambient flow are analyzed. The results indicate that the orientation of the human body to the uniform flow plays a key role.