The present disclosure provides a neutron capture therapy system. The neutron capture therapy system includes an accelerator, the accelerator generates a charged particle beam； a neutron generator, the neutron generator generates a neutron beam after being irradiated by the charged particle beam； a beam shaping assembly, the beam shaping assembly includes a moderator and a reflector surrounds around the outer periphery of the moderator, the moderator moderates the neutrons generated by the neutron generator to a preset spectrum, and the reflector leads the deflected neutrons back to increase the neutron intensity within the preset spectrum； and a collimator, the collimator concentrates the neutrons generated by the neutron generator； the spectrum of the neutron beam is changed by changing the spectrum of the charged particle beam.
