A fabrication method of a wafer structure includes: providing a substrate having a plurality of die regions and an edge region surrounding the die regions defined thereon; then, forming a dielectric layer, a plurality of MEMS devices, a plurality of metal-interconnect structures and a plurality bonding pads on the substrate in the die regions; next, removing the dielectric layer disposed on the substrate of the edge region to expose the substrate; and thereafter, forming a passivation layer to cover the substrate and the dielectric layer.