  We discuss the role of two-neutron transfer processes in the fusion reaction
of the $^{9,11}$Li + $^{208}$Pb systems. We first analyze the $^{9}$Li +
$^{208}$Pb reaction by taking into account the coupling to the $^{7}$Li +
$^{210}$Pb channel. To this end, we assume that two neutrons are directly
transferred to a single effective channel in $^{210}$Pb and solve the
coupled-channels equations with the two channels. By adjusting the coupling
strength and the effective $Q$-value, we successfully reproduce the
experimental fusion cross sections for this system. We then analyze the
$^{11}$Li + $^{208}$Pb reaction in a similar manner, that is, by taking into
account three effective channels with $^{11}$Li + $^{208}$Pb, $^{9}$Li +
$^{210}$Pb, and $^{7}$Li + $^{212}$Pb partitions. In order to take into account
the halo structure of the $^{11}$Li nucleus, we construct the potential between
$^{11}$Li and $^{208}$Pb with a double folding procedure, while we employ a
Wood-Saxon type potential with the global Aky\"uz-Winther parameters for the
other channels. Our calculation indicates that the multiple two-neutron
transfer process plays a crucial role in the $^{11}$Li + $^{208}$Pb fusion
reaction at energies around the Coulomb barrier.
