The invention discloses a low power consumption and high precision resistance-free CMOS reference voltage source circuit, which includes a, a positive temperature coefficient voltage generation circuit and a starting circuit. The self-bias current source circuit uses two NMOS tubes with different threshold voltages in the subthreshold region to form a stack structure, which generates the bias current and negative temperature coefficient voltage on the order of nanoampere. The positive temperature coefficient voltage generation circuit uses PMOS differential to generate positive temperature coefficient voltage for the structure and performs first-order curvature compensation for negative temperature coefficient voltage.