It is important to research the flight control system of tailless aircraft, which has been considered the future aircraft development direction. The gain scheduling method based LPV system was studied, and the polytope model was used to gain-scheduling. A simple but applicable method to convex decomposition was proposed. This decomposition has optimal performance with guaranteed stability. The uncertainties were considered fully, and the robust controller was designed using LMI, which can reduce the constraints and computation. The controller was designed based on LMI. From nonlinear simulation, it can be seen that the controller can control the tailless aircraft to convergence within 0.5s and with small overshoot when the scheduling variable has big variation, and the method was proved feasible in the tailless flight control system.