Abstract: The neutron importance, which is an important parameter of nuclear reactor, means the contribution of the neutron to the reactor power. The 6-group homogenized cross-section of Xi’an Pulsed Reactor was obtained with the cell calculation code WIMS. And the neutron importance distribution was achieved with the diffusion calculation code CITATION. The diffusion calculation was validated with continuous-energy Monte Carlo code MCNP. The space and energy distribution of neutron importance was analyzed. The effect of the neutron importance distribution on the kinetics parameters, namely, the effective delayed neutron fraction and the neutron generation time, were studied. The results show that the neutron importance decreases with the increasing of the neutron energy in the fuel cell. However, in the control rod cell and the central water cell, the neutron importance gets larger with the decreasing of the neutron energy. The reason that the effective delayed neutron fraction is larger than delayed neutron fraction is the importance of the delayed fission neutrons is greater than that of the prompt fission neutrons. And the reason that the neutron generation time is smaller than the prompt neutron lifetime is the neutron importance in the fuel cell is larger than that in the other cells.