The embodiment of the invention discloses a continuous time analog-to-digital converter and a coefficient calibration method thereof. The continuous time Delta-sigma analog-to-digital converter at least comprises a voltage comparator and a digital controller. The method comprises the steps that: a voltage comparator compares a first calibration signal acquired in advance and a preset reference signal in a preset calibration mode, the digital controller calibrates all preset to-be-calibrated coefficients in the continuous time Delta-sigma analog-to-digital converter according to a comparison result of the first calibration signal with the reference signal, wherein the comparison result comprises a high-level signal or a low-level signal.