A low noise amplifier and a radio frequency amplification method using the low noise amplifier are provided. The low noise amplifier includes gain stage circuits, the number of which is not less than that of RF signals to be amplified, and the gain stage circuit is configured to independently amplify the RF signal when being enabled; a plurality of amplification selection switching circuits, each of which is connected to one of the gain stage circuits and is configured to, according to the RF signal, control the gain stage circuit to be enabled or disabled; a plurality of driving circuits, each of which is connected to a respective one of the plurality of gain stage circuits and is configured to, when the gain stage circuit is enabled, receive at least one RF signal amplified by the gain stage circuit and output the amplified RF signal; and at least one load circuit.