The isothermal sections at 700 and 900 °C of the AlSiZr system were determined. The ternary phase τ1 was found at both 700 and 900 °C, while the phase τ2 was only identified at 900 °C. 12 three-phase regions were experimentally determined in isothermal sections of the AlSiZr system at both 700 and 900 °C.