This study considers the event-triggered control problem for linear systems with actuator saturation and external disturbances. First, owing to the impact of the switching event-triggered mechanism, a new method is derived to design the controller and the event-triggered parameters such that the estimation of the domain of attractions is maximised. Compared with the existing results, a larger minimum inter-event interval is presented by combining with a convex analysis approach in stability analysis. Then, this method is extended to the system with disturbances to both guarantee the stability and reject disturbances. Finally, simulation examples are given to demonstrate the superiority of the proposed method.