Employing ab initio calculations and molecular dynamics simulations, we sys-tematically investigated the nucleation of twinning-like lattice reorientation in hexag-onal close-packed metals Mg, Ti and Zr. With lattice expansion and contraction com-panied by local atomic shuffling, homogeneous lattice reorientation requires per atom activation energies of 0.02, 0.035 and 0.04 eV in Mg, Zr and Ti, respectively. Compa-rable to the stacking fault energy on the corresponding pyramidal plane, such activa-tion energy determines the preference of lattice reorientation with respect to conven-tional deformation twinning. Ab initio calculations indicate that certain alloy elements can further decrease the activation energy. Large-scale MD simulations show that the boundary between two grains with twin orientation facilitates the nucleation of lattice reorientation. In particular for Ti with low ductility, lattice reorientation provides rela-tively large normal strain of 8.3% with activation energy of 0.04 eV/atom, and hence may be an efficient mechanism to accommodate plastic deformation.