The invention provides a fabrication method of a deep-groove structure, a semiconductor device and an electronic device. The fabrication method comprises the steps of providing a semiconductor substrate, forming a first groove in the semiconductor substrate, and forming a gap wall on a side wall of the first groove; forming a second groove, under the first groove, in the semiconductor substrate; forming an oxide layer on a surface of the second groove and a part of a side wall, near to the second groove, of the first groove by a thermal oxidation method so that a part, near to the second groove, of the gap wall inclines to seal the second groove; and filling the first groove. By the fabrication method, the favorably-filled deep-groove structure can be formed, and relatively pressure resistance is achieved. The semiconductor device and the electronic device have favorable process stability and the pressure resistance.