Abstract: Smoke and high temperature are the two main factors which threaten the life safety of passengers, drivers and firefighters while a fire accident occurs in a highway tunnel. Based on the existing personnel escape conditions regarding the fire smoke and high temperature respectively, this paper defines a concept of the injury value and life value, proposes a new safety risk criterion for personnel escape with considering both harms resulted from the tunnel fire smoke and high temperature. Taking a bus fire in a highway tunnel as an example, the numerical simulation models are built to analyze the temperature and smoke distribution fields under various fire scenarios. The injury degree of personnel during the escape process at the downstream of the fire, as well as the injury degree of firefighters at different fire-fighting positions are determined according to the proposed new safety risk criterion. The results show that properly increasing the ventilation speed will be of benefit to the personnel escape; the CO is the dominant factor threatening the personnel life safety; the firefighters at the upstream of the fire have enough time to extinguish and rescue when the ventilation speed is higher than 2.5 m/s; in case of ventilation failure, fire extinguishing and rescue time should not exceed 360 s.