A Sigma-Delta modulator and an analog-to-digital converter. The Sigma-Delta modulator comprises a quantizer, a correction module and an RC integrator. The correction module comprises a predetermined resistance through which a correction level is generated. The correction module is used to compare the correction level with a predetermined reference voltage by using a comparator in the quantizer, so as to generate a digital correction signal, based on which the resistance in a resistance correction array in the RC integrator is corrected. The predetermined resistance is of the same type as the resistance in the resistance correction array in the RC integrator. The Sigma-Delta modulator and the analog-to-digital converter can correct the resistance deviation in the RC integrator.