The behavior evolvement of Mg-7.22Gd-4.84Y-1.26Nd-0.58Zr (GWN751K) magnesium alloy during the hot deformation process was discussed. The flow stress behavior of the magnesium alloy over the strain rate range of 0.002 to 2.000 s-1 and in the temperature range of 623 to 773 K was studied on a Gleeble- 1500D hot simulator under the maximum deformation degree of 60%. The experimental results showed that the relationship between stress and strain was obviously affected by strain rate and deformation temperature. The flow stress of GWN751K magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The stress exponent n and deformation activation energy Q were evaluated by linear regression analysis. The stress exponent n was fitted to be 3.16. The hot deformation activation energy of the alloy during hot deformation was 230.03 kJ/mol. The microstructures of hot deformation were also influenced by strain rate and compression temperature strongly. It was found that the alloy could be cxtruded at 723 K with the mechanical properties ofσ0.2 = 260 MPa,σb = 320 MPa, and δ = 18%.