Abstract: For numerical simulation of spontaneous fission neutron source energy, neutron multiplicity and neutron angular correlation distribution, a NESF numerical simulation program is developed to provide fission neutron multiplicity, energy, angular distribution and other parameters on basis of fission process. The program is integrated into existing neutron transport software. This report focuses on background, physical basis, and process of the program, as well as numerical simulation correlated to neutron angular correlation distribution characteristics and nuclear component characteristics.