An AC-AC voltage transformation device is provide, which includes: a first diode (D1), its positive electrode connects to one end of a (AC) power source; a second diode (D2), its negative electrode connects to the joint of D1 and the power source; a third diode (D3), its positive electrode connects to the other end of the power source; a fourth diode (D4), its negative electrode connects to the joint of D3 and the power source, and its positive electrode connects to the positive electrode of D2; a transformer (10), its primary side has a first coil (N1) and a second coil (N2), wherein N1 connects to the negative electrode of D1, and N2 connects to the negative electrode of D3, and its secondary side connects to a load; an electrode switch (SW), one end thereof connects to the joint of D2 and D4, and the other end thereof connects to the joint of N1 and N2.