A casing for a heat-dissipating fan includes a bottom board and a plurality of sidewalls extending from the bottom board. The bottom board and the sidewalls are integrally formed by punching a magnetically conductive plate. The bottom board includes a base on which a stator having a coil assembly is mounted. An axial hole is defined in the base of the bottom board, and a bearing is mounted in the axial hole for rotatably holding a shaft of a rotor. Magnetic pole faces are formed on the base of the bottom board by punching the base of the bottom board. The magnetic pole faces surround the axial hole and are adjacent to the coil assembly of the stator.