The invention relates to a high-linearity folding mixer, comprising a transconductance stage and a mixing core circuit, wherein, the transconductance stage adopts a difference structure, and is composed of two NMOS transconductance units and two PMOS transconductance units; each transconductance unit is formed by two transistors in different sizes in parallel connection; the two transistors are under different bias voltages; one of the MOS tubes biases in a saturation region and is used as a transconductance tube, the other MOS tube biases in a subthreshold region and is used as an auxiliary tube; the two NMOS transconductance units and the two PMOS transconductance units form single-end transconductance amplification stages together; the two single-end transconductance amplification stages form a whole difference transconductance stage. The high-linearity folding mixer has the advantages that 6-7dB of gain can be improved under the condition that an IM3 product keeps unchanging, thusIIP3 is improved by 6-7dB, which improves linearity, and simultaneously improves gain; and the high-linearity folding mixer can be applied in deep submicrometer processing and high frequency communication integrated circuit.