ZnO-based thin film transistors (ZnO -TFTs) were fabricated with Nb/Nd codoped Bi₄Ti₃O₁₂ ferroeledctric thin film as gate dielectric layer.The B3.15Nd0.85Ti 3－xNbxO₁₂ (BNTN x,x=0.01,0.03,5,0.07) thin film was prepared on Pt/Ti/SiO₂/Si(100) substrate by chemical solution deposit ion method.The effects of Nb content on micro-structure,dielectric property and ferroelectricity of BNTNx f ilms have been studied.The BNTN0.03 film has the largest remanent polarization and dielectric constan t,which are 71.4μC/cm^2and 370, respectively.The measured Curie temperature of BNTNx f ilms is about 410℃ and the dielectric loss is around 0.02.ZnO/BNTN ferroelectric TFT,compared with ZnO/SiO₂TFT,has superior outpu t characteristic and transfer characteristic.The values of threshold voltage,cha nnel mobility,memory window and current on/off ratio are 2.5V,5.68cm²/Vs,1.5V and 1.8×10⁵,respectively.