Abstract: The transient liquid phase (TLP) bonding of polycrystalline superalloy GH188 with directionally solidified superalloy IC10 was performed using BNi-2 interlayer material. The effects of bonding temperature on the microstructure evolution and mechanical properties of the joints were investigated in detail. The results elucidated that as the bonding temperature increased, the isothermal solidification process first accelerated and then slowed down, causing the joint strength to first increase and then decrease. When the joint was bonded at 1050 ℃/30 min, a large number of brittle intermetallic compounds (IMCs) were formed near the bonding line due to the insufficient diffusion of melting point depressant elements. When the joint was bonded at 1100 ℃/30 min, complete isothermal solidification occurred and the joint shear strength increased to 634 MPa. Facture occurred at the diffusion affected zone (DAZ). When the joint was bonded at 1150 ℃/30 min, the base materials dissolved and the width of the bonding seam was 1.27 times that of the joint boned at 1100 ℃/30 min. In addition, the joint shear strength decreased to 585 MPa, and the fracture occurred at the athermal solidification zone (ASZ).