Exclusive low-speed lane for large trucks was designed to improve the driving safety of large trucks in continuous downhill section of highways． The driving characteristics of large trucks going downhill under the condi- tion of engine auxiliary braking were analyzed． Based on the brake drum temperature and speed characteristics，it was proposed that there is a necessity to construct an exclusive low-speed lane in continuous long downhill section of highways for large trucks． Taking the six-axis articulated vehicle as the guiding type，the low-speed lane structure system was studied for the driving safety of articulated vehicles when going downhill． the setting method of the low- speed lane was clarified． The lane structures including transition section，buffer zone，steady speed zone and its linear shape were proposed． Then the reasonable speed limit and recommended gear of the low-speed lane was ana- lyzed． Finally，taking a long downhill slope in G5 Jing-kun highway as an example，the temperature rise value of the truck brake drum under various traffic modes was simulated，and the passing safety of the low-speed lane was verified． The results show that，compared with the temperature of brake drum in downhill of free-flow speed lanes and in downhill of limit speed lanes，the temperature of brake drum on downhill bottom of the slow-speed lane is re- duced by 114 and 79 ℃，respectively，and the cooling amplitude can reaches 32. 9% and 25. 3% ，respectively． The maximum temperature in the low-speed lane section is lower than the critical safety temperature． It indicates that setting a low-speed lane in the continuous long downhill section can greatly reduce the rising temperature of the brake drum as well as the probability of brake failure．