This paper investigates an adaptive quantization strategy for networked control systems (NCSs) under an event-triggered control method. Considering the network random delay, event-triggering control method and adaptive quantization, a new type of model of NCS is first built. Specifically, the quantizer is characterized by a sector bound method, which can adaptively adjust the quantization density at the triggering instants. Secondly, by Lyapunov-Krasovskii functional method, sufficient stability and stabilization criteria are obtained to judging the uniformly ultimately bounded stability of the studied system. Then the event-triggered control method parameter and the controller gain are also given simultaneously. Finally, an example is given to demonstrate the potential of the derived approach.