•Evaluated data for Aluminum are validated by a high precision benchmark experiment.•Leakage neutron spectra from pure Aluminum slab are measured at 60∘ and 120∘ using time of flight method.•The experimental results are compared with the MCNP calculations with the evaluated data from different libraries. In the integral benchmark experiment presented here, an aluminium (Al) slab sample (300 mm × 300 mm × 100 mm) was irradiated with Deuterium-Tritium (D-T) fusion neutrons. The neutrons leaking from the sample were detected by a BC501A organic liquid scintillator through the time-of-flight (TOF) method; the neutron energy spectra were derived from the as-obtained TOF curves by considering the detector efficiency. For comparison, some leakage neutron spectra were also simulated by combining a Monte Carlo neutron transport code with evaluated nuclear data from the ENDF/B-VIII.0, JENDL-4.0 and CENDL-3.1 libraries. All the calculated values agreed with the experimental data within 10%, except for a few energy ranges. The values predicted using the ENDF/B-VIII.0 library were lower and higher than the measured ones at below and higher above 4 MeV, respectively; the data based on the CENDL-3.1 and JEDNL-4.0 libraries exhibited some larger differences in the 9.5–12 MeV range at 120∘. The possible causes of these discrepancies are also discussed.