On the basis of static theory and fluid mechanics in porous medium, this paper derives the relationship between the height and radius of water cone in bottom water reservoir with no interlayer using analytic methods, considering radial fluid flow of oil far from the wellbore and the hemispherical centripetal flow of water in immediate vicinity of wellbore respectively. With the analysis of factors affecting water cone, the typical bottom water reservoir numerical conceptual model is established and the water cone shape with a variety of factors is calculated. Using multivariate nonlinear regression method, the relationship between water cone affecting factors and coefficients a1 , a2 , a3 is determined, the quantitative formula of water coning is set up, and the height and volume of water cone is calculated. The validity of analytical methods and quantitative description formula are confirmed with an example of Z1 reservoir. The results indicate that quantitative description formula can satisfy the needs of oilfield.