The invention discloses a transconductance-enhancing passive frequency mixer, which comprises a mixing stage and a biasing circuit, and further comprises a transconductance stage with a transconductance-enhancing function, a passive mixing switch pair and an enhanced load output stage, wherein the transconductance stage with a transconductance-enhancing function transforms an input radio-frequency voltage into a radio-frequency current; and frequency mixing of the radio-frequency current is achieved through the double-balance mixing switch pair, and the current after frequency mixing is transformed into a mid-frequency voltage for output through the transconductance-enhanced load output stage. As the transconductance stage uses a pre-amplifying transconductance-enhancing structure, transconductance is greatly enhanced, thus the same transconductance value can be achieved at a lower bias current, and an output mid-frequency current signal is generated after the radio-frequency current is modulated through the mixing stage. Voltage output is generated through a transresistance amplifier, and finally the mid-frequency voltage signal is obtained. As the transresistance amplifier uses a transconductance-enhancing structure, input impedance is reduced, and current utilization efficiency and port isolation are improved. The transconductance-enhancing passive frequency mixer provided by the invention has the characteristics of low power consumption, high conversion gain, good port isolation and the like.