Abstract: The hot deformation behavior of the fine grained Mg-1.5Bi-0.7Ca (wt%, BX107) alloy was investigated by compressive test using Gleeble 3800 thermal simulator at the temperature of 200 ℃-350 ℃ and strain rate of 0.001 s^-1-1 s^-1. The results indicate that the flow stress of BX107 alloy increases with the increase of the strain rate or the decrease of the deformation temperature. The average activation energy of BX107 alloy during hot deformation was determined to be 227.45 kJ/mol utilizing the hyperbolic sine function constitutive equation. Besides, its constitutive equation was constructed. Additionally, the processing map of BX107 alloy was constructed based on the dynamic material model, and combining with microstructure observation, its suitable processing conditions were determined to be temperature of 300 ℃-350 ℃ and strain rate of 0.001 s^-1-1 s^-1. BX107 alloy exhibits a microstructure softening mechanism dominated by dynamic recovery and continuous dynamic recrystallization.