Based on ab initio evolutionary algorithms, a high-pressure close-packed phase of boron with hexagonal P63/mcm symmetry is predicted, named as B10, which is stable over α-Ga phase above 375 GPa to at least 500 GPa. High pressure makes the typical B12 icosahedron collapse to form an incompressible linear atomic chain arrangement together with an isosceles triangle arrangement. The electron localization function calculations confirm that the B10 has strong covalency in this special atomic arranged structure. The vibration of the three atom's isosceles triangle in the framework of linear atomic chains induces an unusual superconductivity in B10. Electron–phonon calculations indicate that electron–phonon coupling parameter λ is 0.82 and the superconducting critical temperature is 44 K at 400 GPa.