The invention discloses a low-power-consumption and high-gain broadband low-noise differential amplifier, comprising an input unit, a choke unit, a filter unit, an amplifier unit, a load unit, a capacitor C3 and a capacitor C4. The input unit is a two-way differential common gate structure is employed, cross coupling is carried out from a gate to a source of an MOS transistor at an input level, and 50-ohm input impedance is realized at a differential input end through the input unit. The choke unit supplies a direct current access to the ground and chokes an input alternating current signal. A signal current generated by the input unit passes through the filter unit, is amplified by the current multiplexing amplifier unit and then is sent to the load unit, and finally an amplified voltage differential signal is output.