The present application relates to a fabrication method for a double-sided capacitor. The fabrication method for the double-sided capacitor includes the following steps: providing a substrate; forming a stack structure on the substrate; forming a capacitor hole in a direction perpendicular to the substrate to penetrate the stack structure, wherein the stack structure includes sacrificial layers and supporting layers alternately stacked; forming an auxiliary layer to cover the sidewall of the capacitor hole; forming a first electrode layer to cover the surface of the auxiliary layer; removing a part of the supporting layer on the top of the stack structure; removing the sacrificial layers and the auxiliary layer simultaneously along the opening; and forming a dielectric layer covering the surface of the first electrode layer and a second electrode layer covering the surface of the dielectric layer, wherein the gap is at least filled with the dielectric layer.