The electronic structures and elastic properties of metastable Zr 3 N 4 phases have been investigated using the first-principles calculations with the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, in comparison with those of the stable ZrN phase. All three metastable Zr 3 N 4 phases (including orthorhombic, spinel and Th 3 P 4 -type phases) are found to be semiconducting with bandgaps of 1.72-1.94 eV. In particular, the computationally indirect bandgap of 1.72 eV of orthorhombic Zr 3 N 4 is consistent with the experimental value of 1.8 eV. The detailed analyses of the electronic structures reveal that the change of electrical conductivity from metallic ZrN to semiconducting Zr 3 N 4 is mainly due to the electron transfer from Zr to N atoms, which weakens the Zr-Zr interactions and reduces the proportion of metallic bonding. In addition, the elastic properties of Zr 3 N 4 and ZrN phases have been calculated. The theoretical hardness values of ZrN and orthorhombic Zr 3 N 4 are 18.06 and 6.98 GPa, respectively, agreeing well with the experimental values of 19.26 and 7.90 GPa. This work may further promote the understanding of the promising Zr-N material system.