A source driver includes a plurality of shift register groups cascaded in sequence, an enable control circuit and at least one switching circuit electrically connected to the enable control circuit. Each shift register group includes a plurality of stages of shift registers, and is configured to sample digitized image data; a first start signal of an n-th shift register group is output by an (n−1)-th shift register group, n is a positive integer greater than 2. The enable control circuit is configured to output a first turn-on signal or a first turn-off signal. In two adjacent shift register groups, a last-stage shift register in a present shift register group is electrically connected to a first-stage shift register in a next shift register group through a switching circuit.