Abstract: The present invention is to provide a structure of speaker driver, it comprising a base, a drum paper, a yoke, a sound coil and a magnetic unit. The base includes an upper combining portion and a lower combining portion. The drum paper is configured to the upper combining portion. The yoke is configured to the lower combining portion. The sound coil is configured to an underside of drum paper surroundingly. The magnetic unit has a magnet and a front plate, the magnetic unit is configured to above the yoke. Wherein an internal ring surface of yoke has a surface of first poly-magnet and a surface of second poly-magnet, the surface of first poly-magnet is closer to center of yoke than the internal ring surface, the surface of second poly-magnet rises along with the internal of yoke, a bottom of yoke also rises to correspond to the surface of second poly-magnet; an external ring surface of front piece is more distant from center of front piece than an external ring surface of magnet.