A novel topology of buck converter with double frequency is proposed in this paper. This topology is composed of two-buck cells cascaded, one of which works in high frequency, and another one works in low frequency. The current flowing through the high frequency cell is diverted by the low frequency one, and which is reduced rapidly, so the high frequency cell can work in very high frequency without adding soft switching method. But the switching loss of the low frequency cell is low because of the lower working frequency, even though almost all current flows through it. So the high frequency cell can work in higher frequency to improve the steady and dynamic response with lower switching loss. The novel converter topology employs the high frequency cell to improve the dynamic and steady response, and the low frequency one to process the power, so the system performance is enhanced, at the same time the efficiency is also improved. The simulation and experiment results verify the validity of the proposed new topology.