Using density functional theory calculations,we investigate the tetragonal distortion,electronic structure and magnetic property of Pt2MnSn.The results indicate that,when the volume-conserving tetragonal distortion occurs,the energy minimum appears at c/a =0.84,and the energy difference between the minimum and cubic phase is as high as 107meV/f.u.Thus from the point of view of thermodynamics,martensitic transformation may occur in Pt2MnSn with decreasing the temperature.The electronic structure of its cubic and martensitic phases also approves this.Moreover,both the cubic and tetragonal phases of Pt2MnSn are ferromagnetic structures and their total magnetic moments are 4.26μB and 4.12 μB,respectively.