A display device and a chip-on-film structure thereof are provided. The chip-on-film structure includes a substrate, multiple first output pads, multiple second output pads, multiple first lead wires, and multiple second lead wires. The substrate has a surface including a bonding zone. The first and output pads are located in the bonding zone. The first lead wires and the first output pads are located on the same surface of the substrate. The first lead wires and the second lead wires are located on two opposite surfaces of the substrate. Each of the first lead wires is connected to one of the first output pads. Each of the second lead wires is connected to one of the second output pads. The second lead wires each have a portion corresponding to the bonding zone and having the terminal sections that are respectively opposite to the first and second output pads.