Abstract: Superplastic tensile deformation tests of Al-12.7Si-0.7Mg alloy were performed on Instron5500 electronic universal material testing machine. The variations of elongation (δ) and strain rate sensitivity exponent (m) at different strain rates and different temperatures were obtained. The results showed that the strain rate sensitivity exponent and elongation reach up to 0.44 and 379%, respectively, at a temperature of 793 K and the strain rate of 1.67×10^-4 s^-1. The deformation mechanism map inside grains and power dissipation rate map were obtained. The power dissipation rate map was used to predict the processing regime of superplastic deformation. Within the appropriate processing regime, based on the deformation mechanism maps, Burgers vector compensated grain size and modulus compensated stress of Al-12.7Si-0.7Mg alloy at different temperatures were calculated to elucidate the superplastic deformation mechanism.