In order to realize the controllable flight of stratospheric airships during floating, the sliding mode control for lateral trajectory tracking in wind field was researched. The dynamic models of the stratospheric airship during floating were established, and the models were linearized by using linear perturbation theory. The sliding mode controller for lateral trajectory tracking was designed. Considering that this method was insensitive to external perturbation, the trajectory tracking for linear formation and circular was simulated. Simulation results show that the robustness and response characteristic of the trajectory tracking method based on sliding mode control are both satisfactory, and the control accuracy is high in wind field.