Abstract: An adaptive duty cycle adjustment Buck-Boost converter was presented to improve the load transient response ability of traditional PWM peak value current mode. Firstly, combining the actions of adaptive clock control and DAC output variable reference voltage to make rapid duty cycle saturation, it was arranged to further increase the conversion rate of inductor current so as to accelerate the transient response. Furthermore, to solve some problems such as the inherent delay generated by traditional load transient detection and the inability to be applied to systems with Dynamic Voltage Scaling (DVS), a rapid transient detection method was proposed based on duty cycle sampling to be provided with highly accurate, fast detection, and less affected by PVT. Finally, taking 0.18 μm high-voltage BCD process as condition, the proposed method was verified by specific circuit design and domain physical parameters pick-up. The simulation results show that the transient enhancement method proposed in this article can reduce the overshoot/undershoot voltage of load transient response to 33 mV/39 mV under the design environment of clock frequency 1~2 MHz and load current fast stepping from -20 mA to -620 mA in 5 ns. Compared to the conventional PWM peak-current mode operation, the overshoot/undershoot voltage can be reduced by 62%/56% and the overshoot/undershoot recovery time decreases to 5 μs/12 μs, being reduced by 92%/80%. It can provide a theoretic support for speediness transient response of PWM peak-current mode DC-DC.