A system for displaying image includes a driving circuit of a liquid crystal displaying device. The driving circuit of the liquid crystal displaying device includes a shift register, a voltage booster and a sample switch. The shift register receives an input pulse signal and shifts the input pulse signal to output an output pulse signal. The voltage booster is electrically connected with the shift register to receive the output pulse signal, and generates a boost voltage to output a boost signal within the enable time of the output pulse signal. The sample switch is electrically connected with the voltage booster to receive the boost signal. The boost signal controls the sample switch to sample a data signal.