An over-current protection device includes a first substrate, a second substrate, a first grating electrode, a second grating electrode and a positive temperature coefficient (PTC) material layer. The first grating electrode and the second grating electrode are formed on the first substrate and are interlaced and spaced on a same plane. The PTC material layer is formed on the first substrate, the first grating electrode and the second grating electrode, and between the first grating electrode and the second grating electrode. In an embodiment, the first grating electrode and the second grating electrode serve as a current input port and a current output port, respectively.