A source driver circuit includes several sampling-transmitting units each including a first sub-latch unit, a second sub-latch unit and a transmission channel set. In a first period, the first sub-latch unit samples first pixel data. In a second period, the second sub-latch unit samples second pixel data. The transmission channel set electrically couples the first sub-latch unit and the second sub-latch unit to a corresponding digital-to-analog converting unit. In the second period, the first sub-latch unit outputs the first pixel data to the corresponding digital-to-analog converting unit via the transmission channel set. In a third period, the second sub-latch unit outputs the second pixel data to the corresponding digital-to-analog converting unit via the transmission channel set.