Abstarct: With increasing population and consequently, the demand for constructing more roads, more tunnels are constructed to connect these roads together. According to the traffics of tunnels, the ventilation inside these underground structures is very important. A proper ventilation causes the contaminants from combustion of vehicles to decrease and provides better circumstances for breathing for the people in this limited space. The significant role that ventilation system plays in case of fire and dispersion of large volume of smoke inside the tunnel is another substantial reason for the necessity of utilizing appropriate ventilation system in the tunnel. In this research, the best ventilation system for Alavi tunnel, Shaid Rajaei town, Hormozgan is proposed. Using different standards, the necessity of utilizing mechanical ventilation system in there is determined and considering the advantageous of using longitudinal ventilation system, this ventilation approach is selected for Alavi tunnel. The air flow needed for ventilating this tunnel is calculated using both classic methods and the approach presented by PIARC committee. Then, the required pressure drop is computed considering different pressure components. Finally, according to the calculations, two jet fans from two separate company, Novenco and Korfmann is considered for the ventilation of Alavi tunnel. To compare these two jet fans better in case of fire, the tunnel is simulated separately for each jet fan in both normal and fire mode using Fluent software package. As a result, by comparing the outcomes from the software and considering the technical properties of each jet fan, the one from Novenco Corporation is proposed to use in Alavi tunnel.