In　this　study,　we,　for　the　first　time,　report　a　high　Cu　solubility　of　11.8%　in　single　crystal　SnSe　microbelts　synthesized　via　a　facile　solvothermal　route.　The　pellets　sintered　from　these　heavily　Cu-doped　microbelts　show　a　high　power　factor　of　5.57　W　cm(-1)　K-2　and　low　thermal　conductivity　of　0.32　W　m(-1)　K-1　at　823　K,　contributing　to　a　high　peak　ZT　of　approximate　to　1.41.　Through　a　combination　of　detailed　structural　and　chemical　characterizations,　we　found　that　with　increasing　the　Cu　doping　level,　the　morphology　of　the　synthesized　Sn1-xCuxSe　(x　is　from　0　to　0.118)　transfers　from　rectangular　microplate　to　microbelt.　The　high　electrical　transport　performance　comes　from　the　obtained　Cu+　doped　state,　and　the　intensive　crystal　imperfections　such　as　dislocations,　lattice　distortions,　and　strains,　play　key　roles　in　keeping　low　thermal　conductivity.　This　study　fills　in　the　gaps　of　the　existing　knowledge　concerning　the　doping　mechanisms　of　Cu　in　SnSe　systems,　and　provides　a　new　strategy　to　achieve　high　thermoelectric　performance　in　SnSe-based　thermoelectric　materials.