The present invention relates to a limit structure for motor spindle, which includes a base equipped with a shaft tube and a stator set. A limit member and a bearing are disposed inside a shaft tube such that a spindle can be inserted and rotated in the bearing. The inner wall of a through hole of the limit member has plural limit protrusions extended toward a center of the through hole for snapping a necking of a nose of a spindle to limit its axial displacement. The limit protrusion forms a non-vertical included angle with the inner wall of the through hole in a tilted manner. Therefore, when the limit protrusions are subjected to compression of the nose of the spindle, its deformation is so small that irrecoverable condition and fracture of the limit protrusion and rotor drop can be prevented.