A source driver and an operation method thereof are provided. The source driver includes a chopper circuit and a source driver circuit. A first sub-pixel and a second sub-pixel are temporally or spatially adjacent to each other. The chopper circuit adds original gray-scale data of the first sub-pixel with a first value to serve as new gray-scale data of the first sub-pixel and deducts original gray-scale data of the second sub-pixel by a second value to serve as new gray-scale data of the second sub-pixel. The source driver circuit generates a first driving voltage for the first sub-pixel according to the new gray-scale data of the first sub-pixel and generates a second driving voltage for the second sub-pixel according to the new gray-scale data of the second sub-pixel.