Construction vehicles own some inherent characteristics, such as low velocity, high power and following heavy heat flux et al. Aim at decreasing flow resistance and managing airflow, a 39 ton single drum road roller from one of the biggest manufactures in China was employed as a research target to seek out the effect of air flow resistance on the performance of its heat dissipation system. For a start, a simplified 3D model of the road roller in a virtual wind tunnel was established with a commercial software, which was pre-processed in Gambit later. The radiators were set with heat exchanger boundary condition based on the analysis on the air-side elementary unit, as for the cooling fan, the experimental results in the wind tunnel were transformed into the corresponding boundary condition. Following that, a new design scheme was offered to assign the air flow inside the engine cabin, detail flow trajectories of which were introduced by velocity vector and path line acquired from the simulation results in FLUENT. At last, a field experiment was carried out to validate the correctness of the CFD simulation. The results showed that the outlet temperature of thermal fluid from the simulation could agree with experimental data over an acceptable range. The outlet temperature of coolant maintained around 78℃ under the new scheme as ambient temperature was at 30℃, the assignment of air flow path could descend flow resistance, which could improve the heat dissipation performance for construction vehicles as well.