This paper addresses event-triggered control cyber-physical systems under asynchronous denial of service attacks. First, a general attack model is given, which allows us to conveniently model the asynchronous denial of service attacks within measurement and control channels in a unified framework. Then, under a delicate event triggered communication mechanism, a refined switching control mechanism is proposed to account for various attack intervals and non-attack intervals. Furthermore, sufficient conditions are derived for guaranteing the input to state stability (ISS) of the resulting closed-loop system. Finally, a simulation example of unmanned ground vehicle (UGV) is given to demonstrate the validity of the proposed main results.