This study focuses on the transient liquid phase (TLP) diffusion bonding of GH5188, utilizing a BNi-5 interlayer. Parameters were chosen and optimized for GH5188 alloy and the TLP joining mechanism.SThe microstructure evolution and mechanical properties of the joints were comprehensively examined.SThe relatively complete isothermal solidification zone (ISZ) ensured a reliable connection of the base metal (BM).SInS1110 °C to 1190 °C, higher bonding temperature widened the ISZ and enhanced joint composition homogenization, improving mechanical properties.SHowever, an increase in precipitatedSadversely affected the joint"s mechanical properties.SThe maximum shear strength, reaching 482 MPa, was achieved at 1130 °C, representing 84.6% of the BM strength.SWithin theSpressure range of 5 MPa to 15 MPa, both precipitation phases in the ASZ and voids generated by partial melting increased.SOn the contrary, their sizes decreased significantly with higher bonding pressure, resulting in an upward trend in alloy mechanical properties.SThe maximum shear strength of 490 MPa was attained at a bonding pressure of 15 MPa. The joint exhibited a typical mixed fracture pattern, with the small brittle M23C6 phase and voids significantly impacting mechanical properties.SNanoindentation tests indicated the ASZ as a potential source of cracks.