Microstructure and mechanical properties of as-cast and heat treated （T6） ZL205A alloy in sand casting were studied.Phase constituents of as-cast ZL205A alloy were composed of matrix phase of α（Al） solid-solution

of eutectic structure of α（Al）

θ（Al

2

Cu）

Cr phase in dendrite and grain boundary

and of mixture structure of θ and T(Al

12

CuMn

2

) phase on grain boundary as well as a little grey bulk ZrAl

3

and strip Al

3

Ti phase in α（Al） solid-solution.Minor addition of Ti

V

Zr and B into the alloy can significantly refine the grain size.θ phase and Cr phase were dissolved into α（Al） solid-solution and secondary dispersed T phase can be precipitated from the T6 treated alloy.Meanwhile

there exist laminar Al

3

Ti segregation and retained Al

2

Cu phase in crystal boundary.The tensile strength of T6 treated alloy with good toughness which is ductile fracture at different temperatures decreases with temperature increase.