The tunnel thin-film transistor (tunnel-TFT) with polycrystalline-silicon (poly-Si) channel and ferroelectric gate dielectric HfZrO x is fabricated to demonstrate the synaptic characteristics of potentiation and depression in conductance (G d ). Compared to conventional ferroelectric TFT (Fe-TFT), the ferroelectric tunnel-TFT exhibits much lower conduction current and G d due to its unique carrier transport mechanism: interband tunneling. The low conduction current and G d of ferroelectric tunnel-TFT can effectively reduce the power dissipation of neuromorphic computing circuits. Consequently, the ferroelectric tunnel-TFT is demonstrated to exhibit a 5-bit function, low asymmetry, and high G d ratio to meet the requirement of a high recognition rate of neuromorphic computing.