The optimization of mine ventilation system essentially is a very complicated combination optimization, while, ant colony algorithm, which is proposed recently, is a very good method to solve complicated combination optimization problem. In this paper, considering the essence of optimization of mine ventilation system, the ant colony algorithm is introduced to solve the optimization problem of mine ventilation system, in which ventilating network is optimized as the crawl routes of ant colony. So, a new method for optimization of mine ventilation system is proposed here. At last, a mining engineering example is used to verify the applied effects of this new method. The results show that, this method can solve this complicated problem very well, and has better application prospects.