The 3-D numerical model of bifurcation embedded in anchor block concrete of a diversion type power station is built. And FEM is adopted to analyze the pipe stresses and displacement. The influence of initial gap along the penstock outside, concrete’s crack status of anchor block and deformation modulus of the bed rock is discussed. Some conclusions can be achieved as follows. Safe factor is enough when the exposed-penstock design scheme is adopted. But enough rebar is required to guarantee the integrity of anchor block. The initial gap, concrete’s crack and the deformation modulus of bed rock has marked influence on the stresses of penstock. According to the design criteria of reinforced concrete penstocks, combined bearing ability of bifurcation steel and anchor block concrete is advised to reduce the thickness of penstock. As a result, the difficulty of construction is reduced and the investment is more economized than before.