  The proximity of ${\rm Z}^+(4430)$ to the ${\rm D^{*}\bar{D}_1}$ threshold
suggests that it may be a ${\rm D^{*}\bar{D}_1}$ molecular state. The ${\rm
D^{*}\bar{D}_1}$ system has been studied dynamically from quark model, and
state mixing effect is taken into account by solving the multichannel
Schr$\ddot{\rm o}$dinger equation numerically. We suggest the most favorable
quantum number is ${\rm J^{P}=0^{-}}$, if future experiments confirm ${\rm
Z}^+(4430)$ as a loosely bound molecule state. More precise measurements of
${\rm Z}^+(4430)$ mass and width, partial wave analysis are helpful to
understand its structure. The analogous heavy flavor mesons ${\rm Z}^{+}_{bb}$
and ${\rm Z}^{++}_{bc}$ are studied as well, and the masses predicted in our
model are in agreement with the predictions from potential model and QCD sum
rule. We further apply our model to the ${\rm D\bar{D}^{*}}$ and ${\rm DD^{*}}$
system. We find the exotic ${\rm DD^{*}}$ bound molecule doesn't exist, while
the $1^{++}$ ${\rm D\bar{D}^{*}}$ bound state solution can be found only if the
screening mass $\mu$ is smaller than 0.17 GeV. The state mixing effect between
the molecular state and the conventional charmonium should be considered to
understand the nature of X(3872).
