A bandgap reference voltage generating circuit for providing a reference voltage is disclosed. The bandgap reference voltage generating circuit includes four-terminal current source circuit, a regulator circuit and a temperature-compensating circuit. The four-terminal current source circuit outputs a first voltage, a second voltage and a first current which are independent of variation of a first system voltage. The regulator circuit receives the first voltage and the second voltage and when the first system voltage is larger than a threshold voltage value, the regulator circuit outputs the reference voltage independent of variation of the first system voltage via voltage-difference between the first voltage and the second voltage. The temperature-compensating circuit receives the first current and compensates a temperature curve of the reference voltage outputted from the regulator circuit.