  The Bc -> BP,BV decays are studied with the QCD factorization approach (where
P and V denote pseudoscalar and vector mesons, respectively). Considering the
contributions of both current-current and penguin operators, the amplitudes of
branching ratios are estimated at the leading approximation. We find that the
contributions of the penguin operators are very small due to the serious
suppression by the CKM elements. The most promising decay modes are Bc -> Bs
Pi, Bs rho, which might be easily detected at hadron colliders.
