In order to solve the problem of timing mismatch between channels in time-interleaved sampling (TIS) systems, a signal-orthogonality-based timing calibration (SOTiC) is proposed. Based on the signal orthogonality and adaptive iterative algorithm, the estimation and correction of time mismatch parameters in dual-channel TIS system are completed. The multichannel extension structure is derived, and the two-channel correction structure is extended to the M-channel TIS system through odd-even channel recombination. The theoretical and experimental results show that SOTiC has the advantages of fast convergence, small steady-state error, low computational complexity and good scalability, and can be widely used in online correction of timing error in high speed/ultra high speed sampling systems.