Magnetization　and　magnetoresistance　are　significant　for　the　application　of　Ni-Mn-Ga　shape　memory　alloys.　The　Ni46Mn23Ga22Co5Cu4　microwires　with　excellent　mechanical　properties　were　selected　to　investigate　the　influence　of　mechanical　training　on　the　microstructure　and　magnetic　properties.　The　largest　change　of　magnetization　(ΔM)　and　magnetoresistance　fluctuations　were　found　after　training　10k　cycles.　Furthermore,　the　microstructure　and　magnetic　configuration　were　studied　by　TEM,　GPA,　and　MFM　to　investigate　the　mechanical　training　effect　and　the　internal　mechanism.　Nano-precipitated　phases　were　found　embedded　in　the　matrix　and　the　dislocation　stacking　around　the　precipitate　induced　a　local　strain　field　which　could　be　released　during　mechanical　training.　The　magnetic　domain　was　transformed　from　indistinct　into　strip-type　after　training,　which　affects　the　magnetic　properties　of　microwires.　This　work　provides　an　idea　for　improving　the　magnetic　and　magnetoresistance　performance　and　building　a　link　between　microstructures　and　electric　signals　of　shape　memory　alloys.　©　2023　The　Author(s)