The present invention discloses a voltage level conversion circuit. A first and a second N-type driving transistors turn on when a first power voltage source supplies a high state voltage. A voltage transmission circuit transmits a first and a second input voltages having opposite levels to sources of the first and the second N-type driving transistors. A current source operates according to a second supply voltage source and has a first and a second output terminals. A first and a second connection transistors respectively couple between the drain of the first N-type driving transistor and the second output terminal and between the drain of the second N-type driving transistor and the first output terminal. The first and the second connection transistors turn on and off when the first voltage supply source supplies the high state voltage and a low state voltage.