Abstract: Tungsten disulfide (WS₂) is a transition metal chiogenide (TMDs) material, which has a wide adjustable band gap (1.3-2.1 eV), relatively low defect density and high ratio of surface and volume. The carrier transport performance can be improved by external doping or phase transformation treatment. It has broad application prospects in the fields of low power FET and ultra-sensitive photodetector. The multilayer WS₂ thin film was transferred to the hafnium oxide (HfO₂) dielectric layer by micromechanical stripping method, and WS₂ back gate FET with high grid control and low power consumption was prepared. The surface electron doping of WS₂ thin film was realized by injecting trethylamine (TEA). The experimental results show that the in-plane vibration mode of the modified multilayer WS₂ film shifts slightly, and the intensity of Raman characteristic peak weaken, which prove that triethylamine solution could effectively increase the electron concentration in WS₂ film, and the ohmic contact between the film and the metal electrode is good. The electron mobility of the device increases from 10.87 cm²·V⁻¹·s⁻¹ to 24.89 cm²·V⁻¹·s⁻¹. The ON/OFF ratio of output current is 10⁶ at room temperature, and the subthreshold swing is 190.11 Mv/Dec. The doping of TEA as a reducing agent on WS₂ atom thin layer is analyzed in combination with the theory. TEA increases the electron concentration in WS₂ semiconductor by means of surface charge transfer, and completes the n-type doping of WS₂ backgate FET. The higher current switching ratio and improved electron mobility of WS₂ devices prove that the surface modification of TEA can effectively regulate the electron transport characteristics of WS₂ multilayer transistors.