Abstract: Modern plane-symmetric hypersonic vehicles (HSV) typically feature a tailless configuration and small control surfaces, significantly reducing the vehicle’s stability and complicating the vehicle’s lateral and longitudinal control. This paper uses the linear small disturbance theory to develop three-channel open-loop and closed-loop coupled instability criteria for HSV. The criteria include the classical aerodynamic static and dynamic derivatives, forming a new group of three-channel coupled instability criteria. Compared with the existing criteria, this research introduces the static stability coupled criteria and the three-channel dynamic stability coupled criteria in the pitch and roll channels. The critical values of the lateral and longitudinal criteria are no longer zero as the classical criteria by considering dynamic derivative in the pitch channel. Moreover, the effectiveness of the three-channel coupled instability criteria is verified by numerical simulations. The new criteria improves the discrimination method for determining the static and dynamic stabilities and provides a fast and effective tool for stability analysis of this type of vehicle.