Bound states in the continuum (BICs) have long been recognized as topological singularities of light, yet their descriptions have relied solely on scalar topological charges that trace a polarization angle rotation, leaving their true vectorial topology unexplored. Here, we apply the concept of a vectorial topological charge (VTC) to BICs, resolving this fundamental limitation by capturing the full set of winding numbers of ($S_1$, $S_2$, $S_3$) axes on the Poincaré sphere. Using bilayer photonic crystal slabs as a model system, we reveal that nontrivial VTCs can be manifested through pseudopolarization singularity generated by BICs within the perturbation parameter space. Intriguingly, such a VTC further links BICs to counterrotating phase singularities in the upward and downward radiation channels—an effect invisible in scalar frameworks. Moreover, the multicomponent nature of VTCs drives a BIC to split into multiple pairs of half-integer pseudopolarization singularities under symmetry breaking, rather than merely forming a pair of circular pseudopolarization states, thereby defying the conventional rules of topological charge evolution. Our findings reveal a richer vectorial topology that enables control of BICs beyond scalar descriptions.

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• Photonic crystals
• Topological effects in photonic systems