Abstract: Neutron energy spectrum and angular distribution were computed for T(d, n)4He reaction neutron source with 260 keV deuteron beam and TiT 1.5 thick target. The data were applied to simulate the neutron energy spectrum and angular distribution of Lanzhou University 3×10¹² s^-1 intense neutron generator with 260 keV deuteron beam using MCNP. The interactions of neutron and the materials of neutron generator and laboratary wall were included in this MCNP simulation. The simulation results on the neutron energy spectrum and angular distribution of Lanzhou University 3×10¹² s^-1 intense neutron generator with 260 keV deuteron beam were presented. Moreover, the simulation neutron energy spectrum was compared with the experimental neutron energy spectrum for verifying the reliability of Monte-Carlo simulation results.