To　overcome　the　shortcomings　of　the　optical　fiber　coupling　of　a　domestic　higher　power　diode　laser,　an　optical　fiber　coupling　focusing　system　was　designed　and　a　5　kW　optical　coupling　diode　laser　was　developed.　The　optical　fiber　coupling　methods　by　common　circle　spot　and　diode　laser　squarespot　were　compared.　For　a　domestic　array　diode　laser　stack,　the　optical　quality　homogenization,　polarization　beam　bunching,　multi-wavelength　bunching　were　used　to　increase　the　energies,　by　which　the　laser　can　be　coupled　into　the　optical　fiber　with　a　core　diameter　of　800　μm　and　a　Numerical　Aperture　(NA)　of　0.2.　Thus,　the　fiber　coupled　output　power　reaches　5109　W,　the　fiber　coupling　efficiency　is　85.69%,　and　the　electro-optic　conversion　efficiency　of　overall　system　is　49.48%.　Moreover,　the　power　density　reaches　2×105　W/cm2　when　focal　length　is　250　mm.　The　laser　has　been　used　in　multi-wavelength　surface　remelting,　metal　alloying,　laser　cladding　and　laser　welding　fields.　All　the　parts　of　the　laser　are　made　in　China　except　the　optical　fiber　for　energy　transfer,　so　it　promotes　the　progress　of　higher　power　domestic　optical　fiber　coupling　lasers.　©,　2015,　Chinese　Academy　of　Sciences.　All　right　reserved.