This　work　investigates　the　effect　of　Ru　on　the　precipitation　of　the　topologically　close-packed　(TCP)　phase　from　the　gamma-gamma＇　microstructural　degradation　analysis.　The　addition　of　Ru　is　found　to　delay　the　precipitation　time　of　the　TCP　phase　from　100　h　to　1000　h　after　thermal　exposure　at　950　degrees　C.　The　effect　of　Ru　on　the　gamma-gamma＇　microstructural　degradation　is　also　investigated.　Adding　Ru　slightly　decreases　the　coarsening　rate　of　the　gamma＇　size　and　promotes　the　reduction　of　the　volume　fraction　of　gamma＇　phase.　The　reduction　of　the　volume　fraction　of　gamma＇　phase　causes　the　＂inverse　partitioning＂　effect　and　increases　the　solution　limit　of　the　TCP　forming　element　in　the　matrix.　These　help　inhibit　the　precipitation　of　the　TCP　phases　in　Ni-based　single　crystal　superalloys　during　thermal　exposure.