  Beyond the second-order Born approximation, we develop an improved master
equation approach to quantum transport by virtue of a self-consistent Born
approximation. The basic idea is replacing the free Green's function in the
tunneling self-energy by an effective reduced propagator under the Born
approximation. We found that the effect of this simple improvement is
remarkable, for instance, it can not only recover the exact result of
noninteracting transport under arbitrary voltages, but also predict the
challenging nonequilibrium Kondo effect. In addition to having an elegant
structure, the application convenience and accuracy of the proposed scheme, as
demonstrated by the examples in this work, may suggest it a useful tool for
quantum transports.
