Since the energy storage elements in switching converter have a certain response time, it is difficult to respond to the envelope signal rapidly. The dynamic generation technology for control reference in envelope tracking power supply is proposed. This paper uses a low-pass filter to obtain the component information of the radio frequency signal in low frequency, and uses this information to generate a reference signal based on the proposed dynamic average segmentation technology. Switched mode power converter can provide the main part of the low-frequency energies with high efficiency, and the rest of the high-frequency energies can be supplemented by a linear amplifier. The effect of the amplitude and the duration time of the constant reference on the overall efficiency of power supply is discussed in detail. Finally, based on the 64 quadrature amplitude modulation radio frequency signal, a composite envelope tracking (ET) power supply with the tracking bandwidth of 300 kHz and the output voltage of 7.6 V~21 V is constructed. Experimental results verify the feasibility of the proposed method.