Abstract: Neutron detection efficiency is measured using a double scintillator TOF spec-trometer. The principle and the experimental results of the efficiency calibrationare given. 15.2 MeV neutrons are produced through the T(d, n)~4He reaction with 400keVdeuteron beam bombarding a T--Ti target. The hydrogen scatterer is a cylindricalplastic scintillator(φ2.2×3cm). The flight path of the n--p scattering neutron is 2 mand the time resolution is about 1.5 ns. Neutron energy range is 1--14 MeV. Thedata are also corrected for the multiple scattering and finite geometry with aMonte--Carlo code. The overall error is about 2%.