  We study the decay processes of $\bar{B}^0 \to J/\psi \bar{K}^{*0} K^0$ and
$\bar{B}^0 \to J/\psi f_1(1285)$ to analyse the $f_1(1285)$ resonance. By the
calculation within chiral unitary approach where $f_1(1285)$ resonance is
dynamically generated from the $K^*\bar{K}-c.c.$ interaction, we find that the
$\bar{K}^{*0} K^0$ invariant mass distribution has a clear broad peak. Such
broad peak has been understood as the signal of the $f_1(1285)$. Finally, we
obtain a theoretical result $R_t=\Gamma_{\bar{B}^0 \to J/\psi \bar{K}^{*0}
K^0}/\Gamma_{\bar{B}^0 \to J/\psi f_1(1285)}$ which is expected to be compared
with the experimental data.
