With a large number of construction projects building in urban rail construction, it’s very necessary for researching on the construction axis. Construction axis of the subway is consisted of line segment, circular arc segment and transition curve. The paper introduces design models and algorithms of the tunnel boring machine (TBM) axis (DTA). By analyzing the DTA characteristics of each curve, summing up their general characters, we ultimately make a unified common algorithm and geodetic coordinate calculation model of the design axis in horizontal and vertical planes. It will be very useful for the process of underground construction.