Abstarct: In the this work, structure of liquid alkali mextals has been studied using of calculations of structure factor, S(k). In the presented model, direct correlation function, c(r), has been considered into core and tail contributions via the first thermodynamic perturbation theory. The Verlet-Weis equation of hard-sphere fluid was used to describe of core part of c(r) in which the molecular diameter parameter obtains by Barker-Henderson method at any temperature. Tail part of c(r) related to a Yukawa pair potential via a linear form which well depth parameter considered to be effective and can be calculated at any temperature and density. We have used the linear isotherm regularity equation of state, LIR, to calculate inter molecular parameters. Using of presented model we have calculated behavior of S(k), for the liquid rubidium and also the liquid cesium in wide range of thermodynamic states. Calculation results showed a good agreement with experimental data which are available in the literatures. This agreement was better in high densities region of fluids. It is considerable that our model can be show the Ornestine-Zernik behavior of S(k) in small-k region, which is one of advantage of model. Also, the model can is capable to be predict the values of S(0) in different thermodynamic region.