This paper proposes a generation method of dithering signal based on Discrete Fourier Transform (DFT), which is not only independent with the input signal but also can decrease the quantization error of the Analog-to-Digital Converter (ADC). A detailed investigation of three typical dithering effects on the quantization error in ADC has been also presented in this paper, to highlight the advantages of the proposed reconstructed dithering signal. The simulation experiment and theoretical analysis illustrate that the reconstructed dithering signal based on DFT can improve the performance of ADC in comparison with traditional typical dithering signal.