Abstract: Structural design, workmanship and the material--choosing characteristics of sealed--off neutrontube with continual neutron intensity of 2.5×10~9 neutron per second are introduced. The working pa-rameters of the neutron tube are ion source anode voltage 3.3 kV, the ion source discharges current 1.8 mA, the accelerating voltage 134 kV, and the ion beam current is 740μA. It is proved in many teststhat the neutron generator is stable and long service life.