  In the present work, we propose to search the charmonium-like states
$Z_c(3900$) and $Z_c(4020)$ in the $B_c$ decay. In an effective Lagrangian
approach, the branching ratios of $B_c^+ \to Z_c(3900)^+ \pi^0$ and $B_c^+\to
Z_c (4020)^+ \pi^0$ are estimated to be of order of $10^{-4}$ and $10^{-7}$,
respectively. The large production rate of $Z_c(3900)$ could provide an
important source of the production of $Z_c(3900)$ from the semi-exclusive decay
of $b$-flavored hadrons reported by D0 Collaboration, which can be tested by
the exclusive measurements in LHCb.
