In the past decades, tunnel fire safety has been highly concerned since tunnels were widely installed and utilized as transportation links for people and cargos worldwide. In order to achieve a fire safety purpose, smoke extraction system should be well designed and built to extract or control the smoke effectively. The objective of this paper is to investigate the heat and smoke flow behavior based on CFD simulation in a longitudinal ventilated tunnel, Tunel do Monte da Guia (TMG tunnel) in Macau SAR, China. The dimension and the inclination angle of the existing roadway tunnel are of 285m (L) x 10.5m (W) x 7m (H) and 2.45˚, representatively. In this study, a single fire source caused by a vehicle is considered. The smoke flow in the tunnel model is simulated with the CFD program, FDS. In results, the critical velocities are obtained with the tunnel models arranged in the horizontal and inclined positions. Moreover, the smoke temperature is also analyzed in this study.