A driving device includes two rotor assemblies, a stator assembly, and a positioning assembly. Each rotor assembly includes a rotation axis and a rotor. The rotor includes a hollow chamber. The two rotor assemblies include a first rotor assembly and a second rotor assembly, a rotation axis of the first rotor assembly is parallel with a rotation axis of the second rotor assembly, a rotor of the first rotor assembly is at least partially embedded in a chamber of a rotor of the second rotor assembly. The stator assembly is surroundingly disposed at an outer side of the two rotor assemblies and drives a rotor. The rotor driven by the stator assembly causes another rotor of one of the first rotor assembly and the second rotor assembly to rotate. The positioning assembly is located outside of the rotors, and limits the rotors to rotate around corresponding fixed rotation axes.