The invention discloses a voltage conversion circuit and a display device. The voltage conversion circuit comprises a voltage output module, a power supply branch, a voltage conversion module and a switch module. The first end of the power supply branch is connected with a power supply, and the power supply branch converts supplied electric energy outputted by the power supply into a first direct-current voltage. A dimming control signal is inputted into a dimming signal input end of the voltage conversion module, and a pulse width modulation signal is inputted into a modulation signal input end of the voltage conversion module. The voltage conversion module generates a voltage driving signal according to the dimming control signal and generates a switch control signal according to the pulse width modulation signal. The switch module is connected between the voltage conversion module and the power supply branch, and performs overvoltage protection of the power supply branch according to the switch control signal. The voltage output module is connected with the second end of the power supply branch, the voltage conversion module and the electric equipment, and the voltage output module outputs a second direct current voltage according to the first direct current voltage and the voltage driving signal so that the electric equipment can be in a rated working state.