A level shifter with high reliability is shown, which has a cross-coupled pair and a pull-down pair. The cross-coupled pair couples a first power terminal to a first output terminal of the level shifter or a second output terminal of the level shifter. The pull-down pair has a first transistor and a second transistor, which are controlled according to an input signal of the level shifter. The first transistor is coupled between the second output terminal and a second power terminal, and the second transistor is coupled between the first output terminal and the second power terminal. A first voltage level coupled to the first power terminal is greater than a second voltage level coupled to the second power terminal, and the second voltage level is greater than the ground level.