A thin film transistor (TFT) array substrate including a substrate, scan lines and data lines both disposed on the substrate, and pixel structures is provided. A plurality of pixel areas is defined by the scan lines and the data lines on the substrate. Each scan line has a driving signal input terminal and an end terminal. Each pixel area includes a first sub-pixel area and a second sub-pixel area. The pixel structures are respectively disposed in the pixel areas and driven by the scan lines and the data lines. Each pixel structure in the respective pixel area includes a first TFT corresponding to the first sub-pixel area and a second TFT corresponding to the second sub-pixel area. Besides, ratios of a channel width to a channel length of the second TFTs connected to the same scan line increase gradually from the driving signal input terminal to the end terminal.