This paper will present a complete analysis of signal spectra for general time-interleaved systems with the practical nonuniformly holding outputs imposed by the timing-mismatch effects. The analysis reveals first the spectra representation for different-form nonuniformly holding signal and then their closed-form expressions of the signal-to-noise-ratio (SNR), in terms of the number of channels, signal frequency, and jitter errors. Such analysis describes both the timing errors imposed by random clock-jitter and fixed periodic clock-skew. MATLAB simulation results are then presented to illustrate the effectiveness of the derived formula.