  We investigate the influence of the fourth generation of quarks on the
branching ratio, the CP-asymmetry and the polarization asymmetries in $B \rar
\rho \ell^+ \ell^-$ decay. Taking $|V_{t'd}V_{t'b}|\sim 0.001$ with phase about
$10^\circ$, which is consistent with the $sin2\phi_1$ of the CKM and the $B_d$
mixing parameter $\Delta m_{B_d}$, we obtain that for both ($\mu, \tau$)
channels the branching ratio is increased and the magnitude of CP-asymmetry and
polarization asymmetries decreased by the mass and mixing parameters of the 4th
generation of quarks . These results can serve as a good tool to search for new
physics effects, precisely, to search for the fourth generation of quarks($t',
b')$ via its indirect manifestations in loop diagrams.
