An ultra low power dissipation voltage reference source without BJT based on sub-threshold characteristic of CMOS was presented. The current which was independent of temperature was obtained by the sum of currents with negative and positive temperature coefficients, and then converted into a reference voltage. A cascode current mirror was used to increase the power supply rejection ratio(PSRR) and reduce the line sensitivity of the circuit. Based on SMIC 0.18 μm CMOS process, the simulated results showed that the voltage’s temperature coefficient was 2.97 10-5/℃ at a temperature range from-20 ℃to 135 ℃. The line sensitivity was 0.089% at a supply voltage range from 0.9 to 3.3 V. The PSRR was-74 dB at 100 Hz frequency. The power dissipation of the circuit was only 230 nW.