Abstarct: Ventilation is one of the most important steps in underground mining. This is mostly owing to the fact that the ignorance of this prominent step can cause serious dangers for individuals and even mechanized equipment. The Design and implementation of ventilation in underground coal mines is very difficult issue due to the presence of various dust, coal spontaneous and numerous gases. In today’s mining industry with improvement of technology and reduction of surface resources, underground coal mining has been grown dramatically, which it causes the importance of mine ventilation and its implementation in order to provide an appropriate atmosphere for mine workers and equipment. There are several methods to design underground mine ventilation systems, which nowadays, due to the advancement of technology; computers and various software has become more common and widely spread all over the mining industry. In this thesis, at the first step, the ventilation system of one of the Eastern Coal Mines Company’s mines (Western-Razmja) was intended manually and thus, a suitable fan was proposed in this regard. Then, the same system was generated in VENTSIM software carefully in the three-dimensional (3D) space and was evaluated baxsed on the measured values in the manual method. The results obtained by computer simulation illustrated that there is a reliable relation between these two methods. Finally, the total residence of this mine decreased by implementation of some specific variations in ventilation system with considering current intensity. According to the results of the manual study, the overall current intensity of this mine calculated 19.6 m3/s (considering 604.74 Pa in pressure fall). Moreover, in order to modify the ventilation system, 1 ventilator and 10 regulators were used regarding this issue. In addition, a particular ventilator named VOD-16 (16̊ Blade-Angle) was presented. After the implementation of resistance reduction plan using VENTSIM software, it was found that the total current of mine has been reduced by 81 Pa with the rate of 19.6 m3/s in a constant current flow.