A radiation detection system and method for a neutron capture therapy system, which may increase the accuracy of neutron beam irradiation dose of the neutron capture therapy system and find out a fault position in time. The neutron capture therapy system includes a charged particle beam, a charged particle beam inlet allowing the charged particle beam to pass through, a neutron beam generating unit which may generate a neutron beam after a nuclear reaction occurs between the neutron beam generating unit and the charged particle beam, a beam shaping assembly for adjusting the flux and the quality of the neutron beam generated by the neutron beam generating unit, and a beam outlet adjacent to the beam shaping assembly, the radiation detection system includes a radiation detection device for real-time detection of γ rays instantly emitted under neutron beam irradiation.