A driving voltage adjusting circuit includes a digital rheostat, a control chip, a low dropout regulating circuit, and a driving circuit. The control chip is connected with the digital rheostat, and configured for adjusting the resistance of the digital rheostat. The low dropout regulating circuit is connected with the digital rheostat and outputs an output voltage according to the resistance of the digital rheostat. The driving circuit comprising a number of switch elements connected with each other and a driver configured for driving the switch elements, each of the switch elements comprising a first terminal, a second terminal, and a control terminal configured for controlling connection and disconnection of the first terminal and the second terminal; the first terminal and the second terminal connected with the control chip, the driver is connected with the low dropout regulating circuit and output an driving voltage to the control terminal.