An effective way to improve power density of power converter is to increase the switching frequency. The switching frequency of traditional one-cycle controlled chip IR1150 is limited to 200kHz. Therefore , a implementation scheme of one-cycle controlled buck converter up to 1MHz switching frequency was proposed. A combination of UC3825 and TPS28225 was used in the control circuit with UC3825 as the main chip and TPS28225 as the drive chip. The systems principle was analyzed and design guideline was presented according to the main switching device, synchronous rectifying device, output filter and the integrator. A prototype with 1.8V and 5A output was build, and the efficiency could rating up to 80.74%. The experimental results verifies the effectiveness of the proposed scheme.