Digital calibration can be used to aid ADCs in improving their performances. In this paper a calibration method is proposed to reduce the effect of the channel offset mismatch in the time-interleaved ADC, with the calibration circuit in the digital domain. In order to avoid the circuit noise that degrades the calibration performance an averaging algorithm will be employed. A 12 bit two-channel time-interleaved SAR ADC is used to verify the calibration technique. The simulation results using a 65-nm CMOS process show that the calibration can reduce the offset between different channels and improve the SNDR.