Using ab-initio calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA), structural, electronic and magnetic properties of Fe2MnSn full Heusler alloy are calculated within the framework to describe the effect of hydrostatic stress. The total system energy optimization indicates that the ground state corresponds to the hexagonal (D019) structure in ferromagnetic (FM) state. The compound undergoes a structural stress-induced phase transitions under pressure of 7 GPa. The total magnetic moment at the optimized lattice parameters is found 7.19 µB, which does not follow the Slater-Pauling rule. The material tends to rapidly lose its spin polarization under 10 GPa hydrostatic stress.