The fusion neutron yield from a compact neutron source is studied. Laser-irradiated deuterium clusters serve as a precursor of high-energy deuterons, which react with a tritium target and produce copious amounts of neutrons in fusion reactions. The Coulomb explosion of deuterium clusters with initial radius of 5 to 20 nm irradiated by a sub-picosecond laser with intensity ranging from 1015 to 1018 W cm−2 is examined theoretically by a MD model. The dependence of the mean and maximum ion kinetic energy, ion energy distribution function and conversion efficiency of laser energy to ion kinetic energy is investigated. The fusion yield was estimated from an ion beam-target model. A high neutron yield of ∼106–107 neutrons/Joule is obtainable for peak laser intensity of 1016–1018 W cm−2, laser wavelength of 0.8–1 µm and clusters with an initial radius of ∼ 20 nm.