The theoretical calculations indicate that the metal doped BN sheets are potential materials to store the hydrogen and tune the band gap. The BN sheet is a nonmagnetic wide-band-gap semiconductor. We predict that 2D h-BN-like sheet material (h-ScN sheet) has special properties, above all, strong adsorption H2, tuning the band gap and others potential properties. Using Density Functional Theory (DFT), the lattice parameters of Al/Cr doped ScN sheets are optimized, which are still kept on 2D planar geometry, and the band gap and H2 storage are studied. The simulation results show that the ScN sheet is a nonmagnetic narrow-band-gap semiconductor, in which the band gap is only 1.130eV. We find that the H2 molecule can be easily absorbed by Al/Cr doped N in ScN sheet, and the band gap is very easy to be tuned by Al/Cr doped ScN sheet. The band gap decreases from 1.130eV to 0.041eV. So Al/Cr doped ScN sheet is a promising material in storage H2 and tuning the band gap.