A 2.4GHz high linearity downconversion mixer is designed with MOSFET transconductance linearization technique. Multiple gated transistors (MGTR) (or derivative superposition) method is adopted in the structure to increase IIP3 of the mixer as well as its convertion gain isn’t degraded. In order to improve the performance of the mixer further, a LC tank is used in the LO stage and two current steering PMOS transistors in load stage. The Mixer is design in TSMC 0.35um SiGe BiCMOS technology. Simulation results show that the mixer achieves 2.88dBm input 1dB compress point, 16.18dBm third-order input intercept point (IIP3) and the conversion gain is 12.97dB.