In this paper, a sequence switching control (SSC) scheme based on auxiliary parallel inductor is proposed to improve the transient performance of buck converters. The proposed SSC scheme introduces a small controlled inductor in parallel with the output inductor, so as to increase the inductor-current slew rate when it is activated during a load transient. Furthermore, an "n+1" sequence switching strategy is proposed to control the auxiliary parallel inductor. The proposed scheme divides the transient event into n+1 periods. In the former n periods the same small output voltage deviations are designed, while in the last period a smaller deviation is done for a smooth transition from the transient to the steady state. The switching sequence is derived applying the capacitor-charge balance principle for each of n+1 periods. For a given buck converter in experiment, the settling time and the output voltage deviation of the proposed SSC scheme enhance more than 50% and 67% respectively over those of the time-optimal control (TOC) for a 3A load step.