Based on the heightening construction of No.2 dam section of Danjiangkou dam, we analyze the effect of key grooves and anchor bars on the bonding interface between fresh and hardened concrete through 3D non-linear finite element simulation computation. The results show that setting key grooves on the surface between fresh and hardened concrete  can transfer force effectively and facilitate the coordination of dam deformation. Anchor bar can further strengthen the links between fresh and hardened concrete. Due to annual variation of atmospheric temperature and water temperature, tighter links between fresh and hardened concrete are disadvantageous to the tensile stress at upstream dam heel.