Abstract: Due to the effect of such factors as casing string weight and wellbore bending,casing strings have more great frictional drag along with the development of horizontal wells and extended reach wells.The frictional drag is too great that greatly affects favorable running casing.Precise predicting axial force of casing strings in the horizontal well provides important basic data for casing strength design.With the finite element analytic software ANSYS of CAE,the author in this paper simulates ?139.7 mm casing load and deformation of Jiangsha-8 horizontal well,calculates contact force of stiff centralizers and casing transversal displacement between stiff centralizers,and obtains the frictional drag of casing strings in the horizontal well.The calculated model takes casing stiffness and the affect of stiff centralizers acting on the frictional drag into account.The calculated result is fit to the measured data,which indicates that the affect of casing frictional drag acting on axial force is great.Most of the casing between centralizers will contact with borehole walls when the casing between centralizers is too long,decreasing the effect of centralizing.The new calculation method provides theoretical support for drilling engineering design.