The invention discloses a low-voltage complementary metal-oxide-semiconductor transistor (CMOS) band gap reference voltage source which belongs to the technical field of power supplies and micro-electronics. The CMOS band gap reference voltage source comprises a low-voltage amplifier, a first order temperature compensation generating circuit, a high order temperature compensation generating circuit and an output voltage generating circuit, wherein the low-voltage amplifier is used for realizing negative feedback at low power supply voltage; the first order temperature compensation generating circuit is connected with the low-voltage amplifier and used for generating a current item which can carry out first order temperature compensation at low power supply voltage; the high order temperature compensation generating circuit is connected with the low-voltage amplifier and used for generating a current item which can carry out high order temperature compensation in the low power supply voltage; and the output voltage generating circuit is used for generating output voltage. The CMOS band gap reference voltage source operated in the low power supply voltage respectively introduces the low-voltage amplifier to a first order compensation item and a high order compensation item of the reference voltage source and proportionally sums and outputs reference voltage, thereby ensuring that the whole circuit is operated in condition of the low power supply voltage.