Abstract: In this paper, the design method and the practical application of the golden section adaptive robust controller are introduced based upon the all-coefficients adaptive control theory. It is also proved that for second-order plants with unknown parameters, the golden section adaptive controller can make the closed-loop systems stable and dynamic characteristics satisfactory in the starting process when sampling time satisfies certain conditions. The conclusion provides theoretical support for applying adaptive control to the transient process. Finally, the results of simulation research are presented.