The turbine blades of heavy-duty gas turbines require materials with excellent mechanical properties and hot corrosion resistance. DD10, a hot-corrosion-resistant single-crystal superalloy is the candidate material for manufacturing F-class gas turbine blades, which are usually fabricated via precision investment casting and then brazing to seal the core removal process remaining holes on the blade tip. However, there are relatively few studies on the brazing process for DD10 alloy. Herein, it is attempted to conduct brazing on DD10 single-crystal superalloy with a Co-based alloy as brazing filler metal. The microstructure of the brazed joints was analyzed using scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and transmission electron microscopy (TEM). Mechanical properties of the joints were evaluated, and the underlying mechanisms were explored. The results indicate that in conditions of brazing followed by heat treatment, phases such as M₅B₃, M₃B₂, MC, and Ni₃Ti precipitated in the weld zone. Additionally, boron (B) diffusion led to the formation of a molten pool-like structure in the diffusion-affected zone. After heat treatment, the rupture strength of the brazed joints reached 80% and 70% of the base metal's strength at room temperature and high temperature, respectively.