600 °C isothermal section of the Al–Cr–Zn system has been determined by Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (SEM-EDS), and X-ray Diffraction (XRD). Eleven three-phase regions have been identified experimentally at 600 °C. The τ3 and τ4 ternary compounds were identified in this isothermal section and the crystal structures of both phases are cubic. The lattice parameters of τ3 and τ4 are a = 2.1536 nm and a = 1.8323 nm, respectively. The formerly reported τ1 phase was not found. The formerly reported τ2 phase is an extension of Al7Cr. The highest Zn content in γ2 and ν phases is 7.1 at at.% and 6.7 at.%, respectively. The Zn solubility in Al7Cr phase can be up to 10.4 at.%, while that in Al4Cr phase is less than 4 at.%. The clearly phase relation of the Al–Cr–Zn system can lead us to better understand the effect of Cr on the corrosion behavior of metals in the Zn–Al bath and the Hot-dip galvanizing process.