  We describe a new approach called Ket-Bra Entangled State (KBES) Method which
enables one convert master equations into Schr\"odinger-like equation. In
sharply contrast to the super-operator method, the KBES method is applicable
for any master equation of finite-level system in theory, and the calculation
can be completed by computer. With this method, we obtain the exact dynamic
evolution of a radioactivity damped 2-level atom in time-dependent external
field, and a 3-level atom coupled with bath; Moreover, the master equation of
N-qubits Heisenberg chain each qubit coupled with a reservoir is also resolved
in Sec.III; Besides, the paper briefly discuss the physical implications of the
solution.
