A time-domain temperature sensing system for supporting a single-point calibration is disclosed. Under a single calibration temperature, the digital output of the temperature sensing system is adjusted by a calibration circuit to a specific value, and the generated calibration parameter thereof can be stored in the same chip of the temperature sensing system or in an off-chip component such as a non-volatile memory. Accordingly, the drawback which is caused by the high cost of a conventional two-point calibration in prior art is solved.