Abstract: To correctly identify the spatial layer relationship of single line tunnels，based on the in-depth study of the tunnel connection relation of the ventilation network，“auto-bridging” and “virtual double-line” methods for identifying the spatial layer relationship of single line tunnels are put forward for the first time.The “virtual double-line” method can render the ventilation system the double-line graphics of fixed width rapidly and automatically without calculating the coordinates of the double-line points，on which the tridimensional graphics of the ventilation system can be created rapidly and automatically for better identifying the relation between layers of tunnels.These two methods have the advantages of small calculation and high efficiency，and have removed the defects in conventional ones.

Key words: Mine ventilation simulation, Single line, Double line, Identification of layer- relationship of tunnels