Lead (Pb) plays a significant role in the nuclear industry and is extensively used in radiation shielding, radiation protection, neutron moderation, radiation measurements, and various other critical functions. Consequently, the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research, emphasizing its crucial role in the field. Using the time-of-flight (ToF) method, the neutron leakage spectra from three \(^{\text {nat}}\!\) Pb samples were measured at \(60^{\circ }\) and \(120^{\circ }\) based on the neutronics integral experimental facility at the China Institute of Atomic Energy (CIAE). The \(^{\text {nat}}\!\) Pb sample sizes were 30 cm \(\times\) 30 cm \(\times\) 5 cm, 30 cm \(\times\) 30 cm \(\times\) 10 cm, and 30 cm \(\times\) 30 cm \(\times\) 15 cm. Neutron sources were generated by the Cockcroft-Walton accelerator, producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n) \(^{4}\!\) He and D(d,n) \(^{3}\!\) He reactions, respectively. Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C, and the nuclear data of Pb isotopes from four libraries: CENDL \(-\) 3.2, JEFF \(-\) 3.3, JENDL \(-\) 5, and ENDF/B-VIII.0 were used individually. By comparing the simulation and experimental results, improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed. Most of the calculated results were consistent with the experimental results; however, a few areas did not fit well. In the (n,el) energy range, the simulated results from CENDL \(-\) 3.2 were significantly overestimated; in the (n,inl)D and the (n,inl)C energy regions, the results from CENDL \(-\) 3.2 and ENDF/B-VIII.0 were significantly overestimated at \(120^{\circ }\) , and the results from JENDL \(-\) 5 and JEFF \(-\) 3.3 are underestimated at \(60^{\circ }\) in the (n,inl)D energy region. The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values. The results indicate that the theoretical simulations, using different data libraries, overestimated or underestimated the measured values in certain energy ranges. Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.
