A time to digital converter includes a polarity detecting module and a time digital conversion module. The time digital conversion module includes a digital coding unit, a ring vibration enabling unit, multistage differential time delay units sequentially forming a closed loop in series and a plurality of trigger units. Each differential time delay unit includes a first input end, a second input end, a first output end and a second output end. The first output end and the second output end of each differential time delay unit outputs differential signals which are complementary to each other. Mismatching between the ascending and descending time of a phase inverter and sampling of a trigger can be improved to enable signals entering the trigger units to be phase-complementary signals, thus improving the linearity of digital conversion.