We investigate the Landau damping of the collective mode in a quasi-two-dimension repulsive Bose-Einstein condensate by using the self-consistent time-dependent Hatree-Fock-Bogoliubov approximation and a complete and orthogonal eigenfunction set for the elementary excitation of the system.We calculate the three-mode coupling matrix element between the collective mode and the thermal excited quasi-particles and the Landau damping rate of the collective mode.We discuss the dependence of the Landau damping on ...","We investigate the Landau damping of the collective mode in a quasi-two-dimension repulsive Bose-Einstein condensate by using the self-consistent time-dependent Hatree-Fock-Bogoliubov approximation and a complete and orthogonal eigenfunction set for the elementary excitation of the system.We calculate the three-mode coupling matrix element between the collective mode and the thermal excited quasi-particles and the Landau damping rate of the collective mode.We discuss the dependence of the Landau damping on temperature,on atom number in the condensate,on transverse trapping frequency and on the length of the condensate.The energy width of the collective mode is taken into account in our calculation.With little approximation,our theoretic calculation results agree well with the experimental ones and are helpful for deducing the damping mechanics and the inter-particle interaction.