The invention relates to a self-reset adjusting mechanism, including: a mounting base; an adjusting member rotatably mounted on the mounting base; a first reset member mounted between the adjusting member and the mounting base; a limiting member rotatably mounted on the mounting base, the limiting member being provided with, corresponding to the adjusting member, a plurality of clamping tables at different heights, and the position of the adjusting member being adjusted by clamping the adjusting member on the clamping tables corresponding to the limiting member; and a second reset member mounted between the limiting member and the mounting base, when the limiting member is rotated to the limit position, the second reset member being deformed to produce an acting force in a direction the same as the rotation direction of the limiting member to cause the limiting member to be in the limit position, and in this case, the first reset member resetting the adjusting member and exerting a reset acting force on the limiting member, so that the second reset member is restored and the limiting member is reset. The self-reset adjusting mechanism of the invention simplifies a core mechanism of a headrest while ensuring the strength of the headrest, has a simple structure, occupies a small space, and has a large adjustment range and a high impact resistance strength.