Precipitation　of　topologically　close-packed　phases　in　a　high　Mo-containing　nickel-base　single　crystal　superalloy　aged　at　1100　degrees　C　for　1000　h　was　investigated　by　the　spherical　aberration-corrected　transmission　electron　microscope.　The　selected　area　electron　diffraction,　super　EDS　and　high-resolution　transmission　electron　microscopy　were　used　to　analyze　the　TCP　precipitates　in　this　study.　Compositions　of　the　growth　front　and　the　internal　phase　of　the　TCP　phase　are　inconsistent,　while　the　P　phase　and　Laves　are　almost　identical,　confirming　that　the　P　phase　is　transformed　from　the　Laves　phase　rather　than　through　the　nucleation　grew　up.