We study the all-optical switching of the weak probe field via a four-level atom system with the help of a microwave field and electromagnetically induced transparency effect. Here, the microwave field is used for coupling two-folded lower levels to which double dark resonances (DDRs) can arise. The atomic medium is switched from transparent to complete absorption under the DDRs. It is shown that the absorption spectrum, pulse propagations and all-optical switching dynamics of the probe field are dependent on the intensity of the microwave field, applied fields and probe detuning. Furthermore, the switching mode between the probe field and the microwave field can be antisynchronous or synchronous, depending on the probe detuning being adjusted to be equal to zero or ±$\Omega_c$, respectively. Our results possibly are helpful in actual tests to design all-optical switching and optical storage devices in optical communications and signal processing.