The invention discloses an all-CMOS (Complementary Metal Oxide Semiconductor) reference voltage source with a high power supply rejection ratio, which comprises a reference voltage source. The reference voltage source comprises a starting circuit, a current source circuit and a temperature compensating circuit, wherein an output end of the starting circuit is connected with an input end of the current source circuit; an output end of the current source circuit is connected with an input end of the temperature compensating circuit; an output end of the temperature compensating circuit forms an output end of the whole reference voltage source. The working characteristic of an MOS transistor working in a sub-threshold region is utilized by the all-CMOS reference voltage source, a nanoampere-magnitude reference current is generated; power supply noise is rejected by adopting a cascode current mirror. In addition, the all-CMOS reference voltage source not only has the advantages that the chip area is small and the power consumption is low and is only nanowatt-magnitude, but also has the advantages that the all-CMOS reference voltage source has the high power supply rejection ratio, the temperature drift coefficient is low, and the line-voltage regulation is low; moreover, a resistor, a diode and a triode are not used; the all-CMOS reference voltage source is compatible with a standard CMOS process; the layout area is effectively reduced; the production cost is decreased.