A radio frequency (RF) amplification method, comprising: modulating a first digital carrier signal with a digital envelop signal to generate digital RF pulse signals having a first frequency, converting the digital RF pulse signals into analog RF pulse signals, amplifying the analog RF pulse signals to generate an RF output signal, converting an analog feedback signal sampled from the RF output signal into digital feedback signals; demodulating the digital feedback signals with a second digital carrier signal to generate an in-phase (I) signal and a quadrature (Q) signal, and generating an amplitude setting signal for adjusting an amplitude of the digital envelop signal and a phase setting signal for adjusting a phase of the first digital carrier signal according to the I signal and the Q signal. The second digital carrier signal has a predetermined frequency shift relative to the first digital carrier signal, and the second digital carrier signal has a predetermined phase shift relative to the first digital carrier signal. The present invention also provides an RF amplification system and a magnetic resonance imaging (MRI) apparatus.