为实现太赫兹频段多重连续域束缚态（BIC）的可控激发与精准调控，并探索其在传感领域的应用潜力，本文设计了一种新型对称超表面结构，通过对称性工程揭示多模BIC的形成与演化机理。提出基于“外圆内方”金属环单元的超表面结构，采用全波电磁仿真系统研究旋转角度、尺寸变化等对称性破缺参数对BIC模式的影响，结合耦合模理论（CMT）对多模耦合行为进行定量建模，并通过折射率传感仿真评估其性能。该结构在1.25–1.80 THz范围内支持三个对称保护BIC模式，在对称破缺下转化为准BIC，其Q因子随不对称度降低呈指数增长，最高达7372.75；不同方向对称性破缺可独立调控特定共振模式，表现出Fano线型与窄带响应；传感应用中，结构对环境折射率变化表现出高灵敏度（最高501 GHz/RIU）与优异品质因子（FOM=334 RIU^-[1]）。所提出的结构揭示正交维度对称破缺对多模耦合路径的差异化调控机制，所构建传感器在灵敏度与FOM值上显著优于同类器件，解决了高灵敏度与高分辨率难以兼得的难题。

To achieve controllable excitation and precise manipulation of multiple terahertz Bound States in the Continuum (BIC) and explore their potential in sensing applications, this paper designs a novel symmetric metasurface structure. The formation and evolution mechanisms of multi-mode BICs are investigated through symmetry engineering. A metasurface structure based on concentric "square-inside-circular" metallic ring units is proposed. The influence of symmetry-breaking parameters, such as rotation angles and dimensional variations, on the BIC modes is systematically studied using full-wave electromagnetic simulations. The multi-mode coupling behavior is quantitatively modeled using Coupled Mode Theory (CMT), and the performance is evaluated through refractive index sensing simulations. The results indicate that the structure supports three symmetry-protected BIC modes within the 1.25–1.80 THz range, which transform into quasi-BICs under symmetry breaking. Their Q-factors increase exponentially as the asymmetry degree decreases, reaching a maximum value of 7372.75. Symmetry breaking along different directions enables independent control of specific resonance modes, exhibiting Fano lineshapes and narrowband responses. In sensing applications, the structure demonstrates high sensitivity (up to 501 GHz/RIU) and an excellent Figure of Merit (FOM = 334 RIU^-1). Notably, the proposed structure reveals the distinct control mechanism of orthogonal symmetry breaking on multi-mode coupling pathways. The constructed sensor significantly outperforms comparable devices in both sensitivity and FOM, addressing the longstanding challenge of simultaneously achieving high sensitivity and high resolution.