  In this proceeding, we report our recent study of the mixing mechanism
between $D_{s1}(2460)$ and $D_{s1}(2536)$. On the basis of Godfrey-Isgur model,
we consider the $D^*K$ hadron loop effect on the ${}^3P_1$ and ${}^1P_1$
$c\bar{s}$ states. We construct the propagator matrix of these two-state
system, from which we can extract the poles as well as the mixing angles.
Through this method, we simultaneously determine the masses, widths and mixing
angle of these two physical states and the results agree well with the
experimental measurement. Besides the mass shift, we also find that the hadron
loop effects can cause a significant shift for the mixing angles from the value
determined in the heavy quark symmetry limit.
