The invention relates to a high-linearity low noise amplifier which comprises an amplification bias unit and an amplification unit comprising a main amplification tube, wherein the amplification bias unit is connected between first bias voltage and the grid electrode of the main amplification tube. The high-linearity low noise amplifier also comprises an auxiliary unit, wherein the auxiliary unit comprises an auxiliary tube and an auxiliary bias circuit; the source electrode of the auxiliary tube is connected with the source electrode of the main amplification tube; the drain electrode of the auxiliary tube is connected with the drain electrode of the main amplification tube; and the auxiliary bias circuit is connected between a second bias voltage and the grid electrode of the auxiliary tube. According to the invention, the noise performance of the low noise amplifier can not be influenced by the auxiliary tube; at the same time, the bias of the auxiliary tube is far less than that of the main amplification tube, thus power consumption can not be greatly influenced; and finally, one auxiliary tube and the corresponding auxiliary bias circuit are only added, which dose not cause the increase of the area of a chip. Because of universality, the high-linearity low noise amplifier is suitable for being used as the low noise amplifier of a system with high linearity.