Abstract: The Gleeble-3500 thermal simulation testing machine was used to conduct isothermal compression tests of fully equiaxed high magnesium 5XXX aluminum alloy prepared by spray forming. The thermal deformation behavior of fully equiaxed high magnesium 5XXX aluminum alloy was studied under deformation temperature of 350-500℃ and strain rate of0.01-10 s-1. Meanwhile, based on the Arrhenius hyperbolic sine constitutive model, dynamic material model and Prasad theory, the constitutive equation and hot processing map of fully equiaxed high magnesium 5 XXX aluminum alloy were established. The results show that the hot deformation behavior of the high magnesium 5XXX series aluminum alloy prepared by spray forming full equiaxed technology is basically similar to that of the traditional semi-continuous casting aluminum alloy, but there is a processing instability zone with a larger area than that of the traditional casting alloy. Through calculation,the hot compression deformation activation energy of the test alloy is 201.548120 kJ/mol, and the optimal hot working process parameters should be 457-477℃, 0.175-1.872 s^-1.