Abstract: In order to overcome the adverse factors which were brought in by the extraction of positive ions from PIG ion source for neutron tube currently. PIG negative hydride ion source was used as an ion source for neutron tube. Authors investigated the generation mechanism of hydride ions by PIG ion source，which was expected to be applied to neutron tube. The structure of a PIG ion source was given. According to the mode and conditions of hydride ions generation, and to combine with the CST-based simulation experiments, the existence of dense hydride ions placed around opposite cathode and extraction hole was confirmed. In the experiments, the presence and regularity of distribution of hydride ions were proven by the negative ion source generation system, the yield of the 50 mm neutron tube with negative ion source and drive-in target was more than one order of magnitude of that of the conventional neutron tube with positive ion source.