The Λ-type three-level system coupled by two coherent fields is a basic model to study the electromagnetically induced transparency(EIT). Based on that,the cascade quasi-Λ-four-level configuration is formed when a radio-frequency(RF)field drives the transition between the excited state and an additional excited state level. The absorption property is studied along with the parameters of the coupling field and the RF driving field by numerically solving the relevant equations of motion of the density matrix. It is shown that under the applying of the coupling field and the RF driving field,both the Autler-Townes doublet and the EIT are observed in the absorptive spectra and it can be explained properly by the theory of dressed state. An important conclusion is that the Autler-Townes doublet originates from the atom system interaction with the strong RF field,while the EIT originates from atom system quantum interference interaction with the coupling field.