Abstract: Objective The aim was to study microstructure and mechanical properties of IC10 alloy brazed joints by B-Ni55NbCoWCrAlSiMo(C)-S brazing filler metal (B-Ni55 brazing filler metal). Methods Brazing experiments of IC10 superalloy were conducted by B-Ni55 brazing filler metal at brazing temperature of 1 225 ℃ for 30 min with different clearances, and microstructure and mechanical properties of brazed joints were analyzed. Results The results indicated that a strong interfacial reaction occurred between brazing filler metal and base metal during the brazing process. Complete brazed joints could still be formed even with a large clearance of 1.6 mm. Conclusion The average stress rupture life of brazed joints obtained at a clearance of 0.05 mm was 99.5 h under the condition of 980 ℃/75 MPa, and rupture life showed a decreasing trend with the increase of brazing clearance.