The elevated temperature plastic deformation was studied by thermomechanical processes for three kinds of Mg-RE alloys in different temperature and different strain rate. The results show that the flow stress of 1# alloy containing Ce is lower than that of 2# alloy containing Nd, and 3# alloy containing Nd and Y at same temperature and same strain rate. The 1# alloy containing Ce is more suitable for extrusion forming from thermal deformation angle.