A frequency adjustment method, a System-On-a-Chip, and a terminal are provided. In the embodiments of this application, when an access bandwidth requirement on a DDR memory changes, a first frequency adjustment request for a DDR interface is generated using a CPU, and a working frequency of the DDR interface is adjusted. Because during adjustment of the working frequency of the DDR interface, the working frequency of the DDR interface is gradually adjusted according to a predetermined adjustment amount by which a frequency adjustment coefficient of a spread spectrum clocking generator is adjusted each time and a predetermined interval between two adjacent adjustments, it is ensured that a DLL in the DDR interface and a phase-locked loop in the spread spectrum clocking generator are in locking-in states, so that the DDR memory can still be accessed during frequency adjustment of the DDR interface and system performance is ensured.