A neutron monitoring detection system was developed for neutron capture cross-section measurement using a spallation neutron source. A combination of a plastic scintillator and a thin (6) LiF foil was adopted for the detector. The detector system was tested to study the feasibility of the system. Neutron irradiation experiments were conducted with the Accurate Neutron-Nucleus Reaction Measurement Instrument in the Materials and Life Science facility of the Japan Proton Accelerator Research Complex. A neutron time-of-flight spectrum was successfully measured without significant count loss or detector paralysis.