Abstract: As a typical representative of inverse design algorithms, the direct binary search algorithm has been widely used in the design of various optical devices due to its simple principle, fast convergence speed, and high fabrication robustness. This article analyzes the core mechanism and design process of the direct binary search algorithm, sorts out its improvement directions and strategies, focuses on its typical applications in multiple physical dimensions of optical-signal amplitude, wavelength, mode, and polarization, and looks forward to the possible development trends of future research, in order to provide valuable references for related research and promote further inverse-design exploration and application in the photonic-chip field.