We analyze the semileptonic rare decays of $B$ meson to $K_{1} (1270)$ and $K_{1} (1400)$ axial vector mesons. The $Bto K_{1} (1270,1400) ell^+ ell^-$ decays are significant flavor changing neutral current decays of the $B$ meson. These decays are se
nsitive to the new physics beyond SM, since these processes are forbidden at tree level at SM. These decays occurring at the quark level via $bto s ell^+ ell^- $ transition, also provide new opportunities for calculating the CKM matrix elements $V_{bt}$ and $V_{ts}$. In this study, the transition form factors of the $Bto K_{1} (1270,1400) ell^+ ell^-$ decays are calculated using three-point QCD sum rules approach. The resulting form factors are used to estimate the branching fractions of these decays.
