A control device of a radio frequency power amplifier for a magnetic-resonance imaging, MRI, system, coupled to a radio frequency power amplification module (450, 550, 650), the control device comprising: an input signal processing module (410, 510, 610), configured to process an input signal into at least two signals, wherein a first signal of the at least two signals is used for signal detection, and a second signal of the at least two signals is used for signal amplification; a delay module (420, 520, 620), disposed between the input signal processing module (410, 510, 610) and an adjustment module (430, 530, 630), configured to apply a preset fixed delay to the second signal; wherein the adjustment module (430, 530, 630) is coupled between the delay module and the radio frequency power amplification module (450, 550, 650) and configured to generate an adjusted second signal; and a signal processing and control module (440, 540, 640), configured to receive the first signal and generate a control signal, wherein the control signal controls a degree of adjustment of the second signal; characterized in that the signal processing and control module (440, 540, 640) includes an adjustable delay unit configured to impose an adjustable delay on the control signal to change a time difference between the preset fixed delay and a total transmission time from a moment that the first signal is transmitted to the signal processing and control module to a moment that the control signal is transmitted to the adjustment module, such that the adjustable delay unit cooperates with the delay module to ensure that the control signal and the second signal simultaneously reach the adjustment module. an input signal processing module (410, 510, 610), configured to process an input signal into at least two signals, wherein a first signal of the at least two signals is used for signal detection, and a second signal of the at least two signals is used for signal amplification; a delay module (420, 520, 620), disposed between the input signal processing module (410, 510, 610) and an adjustment module (430, 530, 630), configured to apply a preset fixed delay to the second signal; wherein the adjustment module (430, 530, 630) is coupled between the delay module and the radio frequency power amplification module (450, 550, 650) and configured to generate an adjusted second signal; and a signal processing and control module (440, 540, 640), configured to receive the first signal and generate a control signal, wherein the control signal controls a degree of adjustment of the second signal; characterized in that the signal processing and control module (440, 540, 640) includes an adjustable delay unit configured to impose an adjustable delay on the control signal to change a time difference between the preset fixed delay and a total transmission time from a moment that the first signal is transmitted to the signal processing and control module to a moment that the control signal is transmitted to the adjustment module, such that the adjustable delay unit cooperates with the delay module to ensure that the control signal and the second signal simultaneously reach the adjustment module.