The air glide stage is a crucial component of the Trans-medium glider's operational workflow. This study focuses on the impact of the Trans-medium glide function on the design of the glider's air track, analyzing the relationship between the start and end states of air glide, lift-drag ratio, and range. A trajectory model for the Trans-medium glider in a two-dimensional longitudinal plane is established, and trajectory simulation is conducted under two initial conditions: 10000 m and Ma = 0.8, as well as 18000 m and Ma = 0.6. The simulation results indicate that parameters at the end of the air glide path are minimally affected by initial conditions when the vehicle is in a stable glide state. Increasing energy altitude can enhance air gliding range; however, this effect is also influenced by gliding attitude. The energy method's range estimation error is significant for unsteady segments. Reducing the proportion of unsteady stages throughout flight can improve glide energy utilization rate and increase overall range.