Benchmark experiments are indispensable for the development of neutron nuclear data evaluation libraries. Given the lack of domestic benchmarking of nuclear data in the fission energy region, this study developed a neutron leakage spectrum measurement system using a spherical sample based on the \(^{252}\) Cf spontaneous fission source. The EJ309 detector (for high-energy measurements) and CLYC detector (for low-energy measurements) were combined to measure the time-of-flight spectrum using the \(\gamma\) tagging method. To assess the performance of the system, the time-of-flight spectrum without a sample was measured first. The experimental spectra were consistent with those simulated using the Monte Carlo method and the standard \(^{252}\) Cf spectrum from ISO:8529-1. This demonstrates that the system can effectively measure the neutron events in the 0.15 \(-\) 8.0 MeV range. Then, a spherical polyethylene sample was used as the standard to verify the accuracy of the system for the benchmark experiment. The simulation results were obtained using the Monte Carlo method with evaluated data from the ENDF/B-VIII.0, CENDL \(-\) 3.2, JEFF \(-\) 3.3, and JENDL-5 libraries. The measured neutron leakage spectra were compared with the corresponding simulated results for the neutron spectrum shape and calculated C/E values. The results showed that the simulated spectra with different data libraries reproduced the experimental results well in the 0.15 \(-\) 8.0 MeV range. This study confirms that the leakage neutron spectrum measurement system based on the \(^{252}\) Cf source can perform benchmarking and provides a foundation for evaluating neutron nuclear data through benchmark experiments.
