Abstract: The flow behavior of Al-15Si alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator in the temperature range of 300~500°C and strain rate range of 0.001~5 s^-1. The results showed that the flow stress is controlled by both strain rate and deforming temperature. The flow stress decreases with increasing deforming temperature and increases with increasing strain rate, indicating that Al-15Si alloy is a positive strain rate sensitive material. The flow behavior of Al-15Si alloy during high-temperature deformation could be represented by hyperbolic sinusoid function of Zener-Hollomon parameters. Structure factor A, stress level parameter α and stress index n in the analytical expressions of σ are 2.07×10¹² s^-1, 0.026 MPa^-1, 4.61, respectively. The activation energy of the alloy for hot deformation is calculated to be 180.96 kJ/mol.