The structural description for the link between the fast vibrational dynamics and slow diffusive dynamics in glass-forming systems is one of the most challenging issues in physical science. Dynamic crossover is observed in many glass-forming liquids. Different scenarios, such phase transition, partial crystallization or glass transition, are proposed to explain such phenomenon. In this talk, I will discuss the structural origin and its correlation with dynamic transition in supercooled liquids. Particularly, in a model of metallic supercooled liquid, we find that local connectivity as an atomic-level structural order parameter tunes the short-time vibrational excitations of the icosahedrally coordinated particles and meanwhile modulates their long-time relaxation dynamics changing from stretched to compressed exponentials, denoting a dynamic transition from diffusive to hyperdiffusive motions. Our result indicates that long-time dynamics has a structural origin, thus suggesting a structural link the fast vibrational dynamics and the slow structural relaxation in glassy materials.