Element segregation of ZL205A alloy and its effect on liquid density were studied by isothermal quenching. The results show that the solidification rate of the alloy is the fastest between 630 ℃ and 620 ℃, and the solidification rate becomes slow after 620 ℃. The segregation degree of Cu element is the largest, followed by the segregation degree of Mn, V, Ti and Zr elements, which is roughly corresponding to the atomic radius of the element. During the isothermal solidification process of ZL205A, the liquid density increases gradually with the decrease of temperature, and the liquid density increases at different temperature intervals at different rates. The segregation of Cu element has the greatest influence on the residual liquid density, among which Mn, Ti, V and Zr elements have little influence on the residual liquid density.