Zeolites have been widely used in industry owing to their ordered micropores and stable frameworks. The pore sizes and shapes are the key parameters that affect the selectivity and efficiency in their applications in catalysis, sorption, and separation. Zeolites with pores defined by 10 and 12 TO4 tetrahedra are often used for various catalytic processes. To optimize the performance of zeolites, it is extremely desirable to fine‐tune the pore sizes/shapes. The first germanosilicate zeolite with a three‐dimensional 11×11×12‐ring channel system, PKU‐16 (PKU, Peking University) is presented. Nanosized PKU‐16 was structurally characterized by the new three‐dimensional rotation electron diffraction (RED) technique. PKU‐16 is structurally related to the zeolite β polymorph C (BEC, 12×12×12‐ring channels) by rotating half of the four‐rings in double mtw units. A stable germanosilicate with 3D 11×11×12 ring channels, PKU‐16 (see picture), was synthesized with a simple organic structure‐directing agent. Nanosized PKU‐16 was structurally characterized by the new rotation electron diffraction methods. The structure of PKU‐16 is related with zeolite β polymorph C by rotating half of the 4‐rings in the double mtw units.