The invention discloses an adaptive threshold adjusting method for a non-contact intelligent card demodulation system. An additionally-arranged adaptive threshold adjusting circuit in a non-contact IC card is utilized for accomplishment. The adaptive threshold adjusting circuit determines whether a threshold is appropriate according to the number of zeros in a zero number counter. After stabilization of a power-on simulation front end circuit, adjustment is carried out from a greatest threshold downwards, the great number of the zeros means that the threshold is too great, burr generation occurs, a fixed threshold step length is subtracted from a present threshold, after accomplishment of threshold switching of the simulation circuit, next determination is carried out continuously, till the number of the zeros reaches a prescribed range, the threshold reaches an optimum one, or demodulation for a smallest threshold is carried out. According to the adaptive threshold adjusting method, in a field intensity range of 1.5A/m-7.5A/m, for multiple antenna waveforms prescribed in an ISO/IEC14443TypeA protocol, a comparator threshold can be automatically selected, and demodulation data with pause width close to 3mus is outputted.