The present disclosure provides a neutron capture therapy system including a beam shaping assembly. The beam shaping assembly includes a beam inlet a neutron generator arranged into the beam shaping assembly, the neutron generator has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons a moderator adjacent to the neutron generator, the neutrons are moderated by the moderator to epithermal neutron energies a reflector surrounding the neutron generator and the moderator, the reflector leads the deflected neutrons back to enhance epithermal neutron beam intensity a beam outlet and at least a movable member moving away from or close to the neutron generator, the movable member moves between a first position where the neutron generator is replaceable, and a second position where the neutron generator is irreplaceable. The neutron capture therapy system has a simple structure, and the neutron generator is easy to be replaced.
