A bimetal thermal element adapted to assembling into a support. The bimetal thermal element includes: a bimetal strip having a first end and a second end opposite to the first end, and a notch formed at the first end; a heater made of a resistant strip including a linear portion and a wound portion, wherein the linear portion is straight and extending from a first position near the second end of the bimetal strip in a direction parallel to the bimetal strip and the wound portion is wound around the bimetal strip and the linear portion; and an insulating device to insulate the bimetal strip from the heater. With this design, there is also no current within the bimetal strip and its support, so the deflection of the bimetal strip is generated only by the temperature-rise coming from the resistant strip, therefore, it can realize a long tripping time.