Abstract: In order to grasp distribution law of gas concentration of double U-shape ventilation and prevent gas exceeding problem, the paper simulated and analyzed air leakage of goaf at different positions between two crossheadings using Fluent software. It also measured and researched gas emission law on working face. The results of simulation and observation show that changes of the gas concentration of the rear scraper conveyor of the working face, the upper concern and rear return airway are small in the process of advancing the working face; the gas concentrations of tailing way have a big change with the change of position of the working face between the two crossheadings. The gas concentration of the tailing way will be the maximum when the crossheadings are opened, it reaches the minimum when the distance between working face and the opened crossheading is 23 meters, reaches the maximum when the distance is 40 meters, and further increase with the distance increasing. Therefore, the reasonable distance of the crossheadings between return airway and gas drainage way is 40 meters from the perspective of gas controlling, and the distance should be no larger than 50 meters from the economic perspecitve.