Abstract: LiH is designated as a promising moderator and shielding material because of its low density, high melting point and large fraction of H atoms. However, lack of the thermal neutron cross sections of LiH makes numerical calculation deviate from experimental data to some extent. In this paper, the thermal kernel effect of LiH was studied, the phonon spectrum of LiH based on the first principle was calculated, and the models of LiH thermal scattering law and matrix by GASKET and NJOY codes were constructed. The ACE format LiH thermal neutron cross sections for MCNP were generated. Comparison between thermal scattering cross section of ZrH₂ and reference results was done, and the secondary neutron spectra were modified by parabolic behavior of Debye model. These cross section could be used in the modeling of the nuclear propulsion particle bed reactor.