In this study, the effects of discharge angle from an air curtain’s jet have been investigated on aerodynamic sealing of a room with positive pressure ventilation system. For this reason, the modeling of flow, heat transfer and species diffusion has been performed by using OpenFoam® numerical solver. The results show that the jet discharge angle has significant effects on the distribution of parameters such as temperature, concentration of pollutants and occupants’ thermal sensation index. So, by varying the jet discharge angle from +10 (towards the indoor space) to -10 (towards the outdoor space), the average temperature difference between two spaces is reduced to 2.5°C. Also, the mentioned varying in discharge angle causes a significant reduction in the mean concentration of pollutants at the indoor space, from 25ppm to 5ppm. On the other hand, the results indicated that for the discharge angle of -10, the average of occupant’s thermal sensation index is shifting to the cool feeling. Therefore, the mentioned discharge angle can reduce the impacts of outdoor warm conditions on the indoor’s. In other words, the discharge angle of -10 demonstrates the best performance of the air curtain device in thermal and aerodynamic separating of two indoor and outdoor spaces.