An embodiment provides a variable gain amplifying method includes: on a signal path of a radio frequency input signal, amplifying a radio frequency input signal by a plurality of serially-coupled amplifiers; steering currents from the amplifiers and controlling respective gains of the amplifiers; performing gain match on the signal path of the radio frequency input signal; and performing phase compensation on the signal path of the radio frequency input signal. The signal path of the radio frequency input signal further has first and second phase variation trends which compensate each other.