This study develops a new droop-based secondary distributed control strategy with hybrid dynamical form for the islanded microgrids (MGs). Two impulsive control algorithms containing time-varying delays are designed, under which the frequency and voltage restoration and active power sharing accuracy of all distributed generators can be realised with an exponential convergence speed. Compared to the traditional continuous or discrete-time distributed algorithms, the designed impulsive controllers formulate the controlled MG to be a hybrid dynamics, which are more general and applicable for practical power systems. Moreover, some delay-dependent sufficient conditions on the requirements for sparse communication network and impulsive time intervals are derived, in which the time delays do not need to be less than the length of the impulsive intervals. Simulation results on the control parameter analysis, and communication network topologies validates the developed theories.