A time-interleaved analog-to-digital conversion apparatus is disclosed. The time-interleaved analog-to-digital conversion apparatus is applied for a television system and includes an input multiplexing module, a gain multiplexer and an analog-to-digital converter. The input multiplexing module receives a plurality of image signals, and samples the image signals according to a clock signal to generate a sample multiplexing signal. The gain multiplexer receives a plurality of gain signals and selectively transmits one of the gain signals corresponding to the sample multiplexing signal according to the clock signal, so as to generate a gain multiplexing signal. The analog-to-digital converter receives the sample multiplexing signal, the gain multiplexing signal and the clock signal. The analog-to-digital converter amplifies and converts the sample multiplexing signal to a digital signal according to the gain multiplexing signal and the clock signal.