  We have analyzed a five-level $\wedge$-configuration Four-Wave Mixing (FWM)
scheme for obtaining a high-efficiency FWM based on the two electromagnetically
induced transparency. We find that the maximum FWM efficiency is nearly 30%,
which is orders of magnitude larger than previous schemes based on the two
electromagnetically induced transparency. Our scheme may provide a new
possibility for technological applications such as nonlinear spectroscopy at
very low light intensity, quantum single-photon nonlinear optics and quantum
information science.
