Overcurrent protection device with graded protection

The invention provides a graded protection over-current protection device, and belongs to the technical field of over-current protection, and the device comprises a PTC element which comprises a first surface and a second surface opposite to the first surface; the first bonding pad group is arranged on the first surface of the PTC element; the second bonding pad group is arranged on the second surface of the PTC element and is used for being mounted on the circuit board in a surface mounting manner; and the fusing alloy is assembled on the PTC element through the two first bonding pad groups, so that the fusing alloy and the PTC element are connected in parallel. The beneficial effects are that the fuse alloy and the PTC element are connected in parallel, large current protection is provided in a loop, and grading protection with a small current protection effect is still provided after primary protection; meanwhile, the fusing alloy is assembled on the PTC element through the first bonding pad set, assemblin