Provided is a radiation detection system for improving the accuracy of a neutron beam irradiation dose for a neutron capture therapy system. The neutron capture therapy system includes a charged particle beam, a charged particle beam inlet for passing the charged particle beam, a neutron generating unit for generating the neutron beam by means of a nuclear reaction with the charged particle beam, a beam shaping assembly for adjusting flux and quality of the neutron beam, and a beam outlet adjoining to the beam shaping assembly, the radiation detection system includes a radiation detection device arranged within the beam shaper or outside the beam shaping assembly, the radiation detection device is used for real-time detection of the overflowing neutron beam by the neutron generating unit or the generated γ-ray after the nuclear reaction of the charged particle beam with the neutron generating unit.