The Imjingang Belt preserved the deformation and metamorphism of rocks related to the Permo-Triassic continental collision between the North and South China Cratons. To understand the microstructural evolution of amphibolites, microstructures of hornblendes in Yeoncheon amphibolites and psammitic schists were analyzed using electron back-scattered diffraction mapping and transmission electron microscopy. Two different types of lattice preferred orientations (LPOs) of amphibole were observed: type- II and type-IV. The subgrain boundaries of hornblende, misorientation axes distribution of hornblende, and existence of relict clinopyroxenes inside the amphibole indicate that the type-IV LPO of amphibole resulted from deformation by dislocation creep and topotactic growth of hornblende. The low-angle boundaries of hornblende associated with cracks and fractures in some samples indicate that type-II LPO of amphibole resulted from cataclastic flow associated with rigid body rotation during retrogression. The seismic velocity and anisotropy of the Yeoncheon amphibolites showed that the seismic anisotropy of the amphibolites followed that of the hornblende. Seismic anisotropy of the amphibolites with type-IV LPO of amphibole was significantly weaker than that of the amphibolites with type-II LPO, suggesting that the fabric transition from type-IV to type-II LPO of amphibole may significantly strengthen the seismic anisotropy of the amphibolite.