  In the framework of the factorization and the heavy quark effective theory,
$B\to D_2^*\pi$ modes are analyzed. We adopt the result from the QCD sum rule
calculation for the hadronic matrix elements at leading order of $\Lambda_{\rm
QCD}/m_Q$ and $\alpha_s$. The QCD sum rule results are well compatible with the
current data, with the prediction on the branching ratios $\calB(\Bbar^0\to
D_2^{*+}\pi^-)=8.94\times 10^{-4}$ and $\calB(B^-\to D_2^{*0}\pi^-)=9.53\times
10^{-4}$ for $N_C^{\rm eff}=2$. We give constraints on the interception
$\tau(1)$ and the slope parameter $\rho^2$ of the leading Isgur-Wise function
from the experimental bounds. It is argued that the observation of nonzero
$\calB(\Bbar^0\to D_2^{*0}\pi^0)$ directly measures the nonfactorizable effets.
