The invention discloses an analog-to-digital conversion method and an analog-to-digital conversion device. The analog-to-digital conversion method comprises the following steps: acquiring an INL curveof an ADC to be calibrated and an output code value, wherein the INL curve carries at least two curve inflection points marked in advance; obtaining a fitting function of the INL curve according to the coordinates of the curve inflection point on the INL curve; and according to the fitting function, the output code value is calibrated and then is output, so that the output precision of the to-be-calibrated ADC can be improved, and the requirement of a high-precision application scene is met.