Incoherent　twin　boundaries　(ITBs)　can　significantly　affect　the　mechanical　properties　of　twin-structured　metals.　However,　most　previous　studies　have　focused　on　the　deformation　mechanism　of　the　coherent　twin　boundary　(CTB),　and　metals　with　ITB-accommodated　plasticity　still　require　further　investigation.　In　this　study,　deformation　mechanisms　of　FCC-structured　nanocrystal　metals　with　ITBs　were　investigated　using　molecular　dynamic　(MD)　simulations.　We　revealed　that　three　deformation　mechanisms　occur　in　metals　with　ITBs.　The　first　type　of　deformation　was　observed　in　Au,　where　the　plasticity　is　governed　by　partial　dislocation　intersections　with　CTBs　or　reactions　with　each　other　to　form　Lomer-Cottrell　(L-C)　locks.　In　the　second　type,　found　in　Al,　the　deformation　is　governed　by　reversible　ITB　migration.　The　third　type　of　deformation,　in　Ni　and　Cu,　is　governed　by　partial　dislocations　emitted　from　the　ITB　or　the　tips　of　the　stacking　faults　(SFs).　The　observed　L-C　lock　formation,　as　well　as　the　reversible　ITB　migration　and　partial　dislocation　emission　from　the　tips　of　SFs,　have　rarely　been　reported　before.