This letter proposes a precision-improved sampling switch that requires only two additional transistors and one inverter, with all devices implemented using N-type transistors. The design introduces a source-drain shorted dummy transistor to compensate for or cancel out the charge injection from the main switch, and incorporates an additional discharge switch with a negative power supply bias to suppress charge leakage and switch soft conduction phenomena. Based on a 7 μm channel length IZO TFT process, simulation results demonstrate that the proposed sampling switch achieves 0-10V full-swing input and output under VDD=10V and a sampling rate of 20kHz, the proposed switch achieves a 0-10 V full-swing input and output. At an input signal frequency of 107.42 Hz, the signal-to-noise and distortion ratio (SNDR) reaches 77.98 dB. The spurious-free dynamic range (SFDR) is improved by 33.36 dB. This design offers an effective approach to improve the sampling accuracy of TFT integrated circuits.