Our work study trap evolution in TiN/Hf_0.5Zr_0.5O₂/Interlayer/Si FeFET with different interlayers (SiO₂ or SiON) during endurance fatigue by the gate leakage current. We comprehensively consider direct tunneling, Fowler-Nordheim tunneling, and trap-assisted tunneling to simulate the leakage behavior. By the experimental and calculated results, we found that the trap-assisted tunneling in FeFET is mainly leakage mechanical which is determined by traps in the interlayer. Less charge trapping and trap generation appears in SiON interlayer sample due to its higher energy level and lower density of traps. And, the main trap in the gate structure is oxygen vacancy.