In accordance with the cracking seriousness of anchor block of some high water head hydropower stations, a 3D FEM analysis on jointly bearingload of the steel bifurcation and outer reinforced concrete was carried out by means of the nonlinear analysis module in ANSYS software. On the basis of the analysis results of the two control conditions and by comparison with the exposed steel bifurcation, the calculated results are concluded that the steel linedreinforced concrete bifurcation and outer reinforced concrete, in which some reinforcing bars are arranged in the anchor block and considered to bear internal water pressure with the steel bifurcation jointly, can reduce the thickness of pipe shell and the dimension of the strengthening beam so as to simplify the technology and reduce the cost of the project. Furthermore, this kind of structure? can enhance the integrity of the anchor block, avoid the serious cracking in concrete caused from the high water pressure, and, thereby, guarantee the long term safe operation of the steel bifurcation and anchor block. So this type of bifurcation will have a better development in future.