The invention discloses a broadband low-noise amplifier. A cascode structure is adopted. The broadband low-noise amplifier comprises a common-source structure MOS transistor M1, a common-gate structure MOS transistor M2, an input matching capacitor C1, a grounding capacitor C2, an output matching capacitor C3, a first inductor L1, a second inductor L2, a first resistor R1, a second resistor R2 and a third resistor R3. An input matching structure of the amplifier is formed by parasitic resistors between a grid electrode and a source electrode of the input matching capacitor, between a grid electrode and a source electrode of the first inductor and between grid electrodes and source electrodes of the common-source MOS transistors together. Through the parasitic resistors between the grid electrodes and the source electrodes of the common-source MOS transistors and the input matching capacitor added between an input port and the ground, the input matching property of a circuit can be effectively improved. The broadband low-noise amplifier is simple in structure, low in power consumption, high in integration degree and suitable for being applied to low-power-consumption broadband.