This paper is contributing to designing a novel event-triggered control (ETC) policy for switched linear systems, where control systems obtain sampling information only at sampling instants. First, by allowing the length of any sampling interval to exceed the minimum DT of all system modes, an innovative aperiodic sampling programme is presented to avoid the high-frequency sampling. Then, based on the proposed aperiodic sampling method, three improvements are presented: (1) a novel aperiodic sampled-data-based event-triggered mechanism (ASETM) is developed, which is more flexible in scheduling communication resources than periodic sampled-data-based event-triggered mechanism (PSETM); (2) a multiple discontinuous Lyapunov function (MDLF) with adjustable sampling-dependent parameters is constructed, which covers the multiple Lyapunov function (MLF) as a special case and further increases the design flexibility; (3) the state-feedback controller gains and event-triggering parameters are sampling-dependent, which broadens the feasible solution range of matrix inequalities. It is shown that by choosing an appropriate aperiodic sampling intervals sequence and sampling-dependent parameters, a tighter bound on the mode-dependent average dwell time (MDADT) and larger sampling intervals can be achieved. Finally, an example is adopted to illustrate the effectiveness of the proposed approach.