A research has been conducted on the delay-delay related stability of the self-balancing vehicle control system. Firstly, by applying Newtonian classical mechanics, a mathematical model of the self-balancing vehicle has thus been established, providing the instantaneous mechanical balance equation of the self balancing vehicle, followed by a linearization of the control motor model. On this basis, an overall state-space model of the self-balancing vehicle system, which incorporates a PID controller with transmission delay taken into consideration, has been established. Using the Lyapunov-Krasovskii (L-K) functional method and a generalized free matrix integral inequality technique, a delay-dependent stability criterion is established for an assessment of delay stability margin of the system. Then, based on the given stability criteria, by using the linear matrix inequality (LMI) toolbox in Matlab, a research has been conducted on the influence of speed loop PID parameters on the time delay stability margin of the self-balancing vehicle control system. Finally, the validity of the proposed system stability criterion is verified through simulation experiments.