Abstract: Mine ventilation simulation system usually uses single-line to draw and display ventilation system graphics and can’t reflect layer relationship among tunnels.The paper put forward a new and high-efficient automatic drawing method of double-line graphics for ventilation system creatively,namely ("virtual) double-line".It introduced natures and characteristics of the "virtual double-line" method,implementation mechanism and steps of rendering ventilation system double-line graphics rapidly and automatically and its implementation method.The "virtual double-line" method(needn’t) calculate coordinate of the double-line points and can render ventilation system double-line graphics rapidly and automatically,and the double-line graphics can reflect layer relationship among tunnels,which has characteristics of less calculation,high execution efficiency.