A channel circuit of source driver and an operation method thereof are provided. The channel circuit includes a digital-to-analog converter (DAC), a first switch, an output buffer circuit and a pre-charge circuit. The terminals of the first switch are coupled to the first output terminal of the DAC and the first input terminal of the output buffer circuit, respectively. The pre-charge circuit is coupled to the first input terminal of the output buffer circuit. The pre-charge circuit pre-charges the first input terminal of the output buffer circuit when the first switch is turned off during a pre-charge period, and not to pre-charge the first input terminal of the output buffer circuit when the first switch is turned on during a normal operation period.