The physical properties of tetragonal DySe2 have been systematically reported by using the first-principles method. We systemically studied the mechanical properties of tetragonal DySe2 under pressure including elastic constants, bulk modulus, shear modulus, Young's modulus. These results show that tetragonal DySe2 intermetallic compound is satisfy mechanical stability within the scope of 0 to 10 GPa. Meanwhile, Pugh's modulus ratio, Poisson's ratio, Vickers hardness, and Debye temperature as well as B/G values under high pressure are further investigated. The ductility, hardness, and Debye temperatures increase with pressure. And the tetragonal DySe2 behaves as a brittle material at ambient pressure and has more ductile under pressure.