A method for fabricating an interposer structure includes: providing a substrate; forming a first opening and filling a first conductive layer in the first opening; forming a first dielectric layer on a first surface of the substrate and forming a first redistribution metal layer in the first dielectric layer; forming a second opening and filling a second conductive layer in the second opening; forming a second dielectric layer on a second surface of the substrate and forming a second redistribution metal layer in the second dielectric layer. Through the redistribution metal layer for wiring is formed on both sides of the substrate in the thickness direction, the high-intensity interconnection requirements can be satisfied. The first opening and the second opening are formed from both sides of the substrate in the thickness direction, respectively, and communicate with each other to make up a TSV hole.