The word isoparametric is used when the same shape functions called as interpolation functions [N] to define theelement's geometric shape as well as used to define the displacements within the element. The Isoparametric elementequations are formed by using an intrinsic coordinate systems i.e. natural coordinate system that is defined byelement geometry and It is not defined by the orientation of the element in the global-coordinate system. In this paperthe Isoparametric formulation for simple bar element is explained first and it will lead to a simple mathematicalcomputation. Then the Numerical Integration for Gauss Quadrature for two and three sampling points is explained.