Abstract: This paper briefly introduces the aboveground layout scheme and integral sinking layout scheme of conventional island of nuclear power plants.Technological-economic analysis formula are given,as a result,main factors influencing scheme selection is obtained.Determination of the layout scheme selection and optimization direction through the curve between the accumulative NPV and related factors is brought forward.The paper carries out the technological-economic comparison to the two schemes referred to a 1000MW level nuclear power project as the example,getting the curve between the accumulative NPV and the plant ground elevation,and offering the method of selecting the vertical layout scheme of conventional island and vertical layout optimization direction.