The invention relates to a differential time domain comparator circuit which comprises a differential voltage time converting circuit, a phase discriminator circuit and an output generating circuit, wherein the differential voltage time converting circuit is used for converting two analog differential input signals to be compared into two pulse signals; the delayed time of the pulse signals relative to a clock signal is in direct proportion to the size of the input signals; the differential voltage time converting circuit can be turned off after a comparison result is generated to decrease power consumption; the phase discriminator circuit is used for determining a phase relation between the two pulse signals; and the output generating circuit generates the comparison result according to the output of the phase discriminator circuit. The invention has the advantages of low power consumption, relatively strong capacity of resisting interference and the like. The differential time domain comparator circuit can decrease circuit power consumption, inhibit even harmonic and improve the precision of an analog-digital converter when being used in a successive approximation analog-digital converter.