Abstarct: Ventilation network design is aimed to establishing adequate air flow in all parts of mine, but the actual results are different to those obtained from prediction design. Thus after performing designed plan, qualification of mine ventilation must be considering and where it is necessary, fixing the issues. Computational fluid dynamics (CFD) modelling is s rapid, accurate, low costs and reliable method for fluid behavior investigation that used in considering of ventilation network. In this study, after detailed checking of western Razmja coal mine ventilation system, one of the ventilation system parts is chosen for modeling. This part is divided into 3 models including, main tunnel model with the direction of air flow to the extraction stop, auxiliary ventilation model and extraction stop model. After developing of CFD model, target areas was fulfilled with respect to dead air identification criteria, evaluation of the explosion risk, identify the areas that disposed for coal self-burning, identify the areas that had fresh air wastage and evaluation of fresh air qualification. The results are showing that in air way to the stop, due to ventilation door devastation, 52% of air, are conducted to the dirty air outlet. Also, in some parts of way, the air velocity was lower than allowed limitation. Thus solutions are developed for these problems. It was found that in evaluation of auxiliary ventilation model, although air velocity is not lower than allowed limitation, but could not supply air qualification requirements and the gray of methane gas is 4 times of allowed limitation. Also, the air recirculation was identified near the face. The evaluation of extraction stop model, shows that conditions prevailing in extraction stop is appropriate, with regard to ventilation, but from the standpoint of ventilation, in caved part, middle part is disposed for self-burning.