Time-interleaved ADC (TIADC) system's poor performance due to mismatches including offset, gain mismatches, and clock skew in sub-channels has restricted its practice use seriously. In this paper, we developed an estimation algorithm for those mismatches, and a digital-background calibration method based on cubic spline interpolation to decimate skew error is also demonstrated. Simulation results show that the TIADC performance can be enhanced and spurious free dynamic range (SFDR) is improved significantly.