It is suggested that the dressed-state electromagnetically induced transparency (EIT) can be used as an efficient way to produce light amplification and quantum noise reduction. The four-level tripod atoms are studied in the scheme by dressed-state atom and collective-mode approach. On two-photon resonance, two strong coherent fields induce the depopulation of a coherent superposition state of two lower states, which leads to quantum beat between the cavity modes. While the two strong coherent fields dress the atoms, the system is simply reduced to a standard EIT model, in which the laser transition, the coherent coupling, and the spontaneous decay constitute a successive population transfer channel to recycle the laser electron. It is for the very mechanism that the cavity modes oscillate with high intensities and exhibit squeezing.