Using first principles within the framework of density functional theory, the structural and magnetic properties of CrSn are investigated. From total energy calculations, we have observed that the binary alloy, CrSn, could crystallize in hexagonal symmetry with the space group of P63/mmc. The spin polarized calculations suggested that the ground state of CrSn is antiferromagnetic. We have followed the Fixed Spin Moment (FSM) approach to study the metamagnetism. The physical cause of metamagnetism in CrSn is found to be the lattice strain. With negative strain (i.e. when the volume of the unit cell is expanded), the total magnetic moment per unit cell abruptly increased from 3.66 μB to 6.07 μB.