The unstable nucleus 5He emission has never been included in the widely used statistical model codes as the evaluation tool and interpretation experimental data. The calculated threshold energies of 5He emission from light nuclei to heavy nuclei indicate that in most cases the compound nucleus induced by incident neutron would emit 5He rather than 3He. Since 5He is unstable and can be separated into n+a spontaneously, so neutron is produced in 5He emission process. The formulation of the double-differential cross section of the neutron from the two-body breakup process of emitted 5He is established. Because of the strong recoil effect, the energy balance is strictly taken into account to meet the needs in nuclear engineering. Further improvement of the statistical model calculation codes on this respect is proposed. It is expected that the correlative measurement will be available to account the outgoing neutron and alpha particle simultaneously and to test and verify the existence of 5He emission. The unstable nucleus 5He emission has never been included in the widely used statistical model codes as the evaluation tool and interpretation experimental data. The calculated threshold energies of 5He emission from light nuclei to heavy nuclei indicate that in most cases the compound nucleus induced by incident neutron Since 5He is unstable and can be separated into n + a spontaneously, so neutron is produced in 5He emission process. The formulation of the double-differential cross section of the neutron from the two-body breakup process of Because of the strong recoil effect, the energy balance is strictly taken into account to meet the needs in nuclear engineering. Further improvement of the statistical model calculation codes on this respect is proposed. It is expected that the correlative measurement will be available to account the outgoing neutron and alpha particle simultaneously and to test and verify the existence of 5He emission.