This　paper　is　mainly　concerned　with　the　global　existence　and　asymptotic　behaviour　of　classical　solutions　to　the　three-dimensional　(3D)　incompressible　non-resistive　viscous　magnetohydrodynamic　(MHD)　equations　with　large　initial　perturbations　in　a　3D　periodic　domain　(in　Lagrangian　coordinates).　Motivated　by　the　approximate　theory　of　the　ideal　MHD　equations　in　Bardos　et　al.　(Trans　Am　Math　Soc　305:175–191,　1988),　the　Diophantine　condition　imposed　in　Chen　et　al.　(Sci　China　Math　64:1–10,　2021)　and　the　magnetic　inhibition　mechanism　in　the　version　of　Lagrangian　coordinates　analyzed　in　Jiang　and　Jiang　(Arch　Ration　Mech　Anal　233:749–798,　2019),　we　prove　the　global　existence　of　a　unique　classical　solution　with　some　class　of　large　initial　perturbations,　where　the　intensity　of　impressed　magnetic　fields　depends　increasingly　on　the　H17×　H21　-norm　of　the　initial　velocity　and　magnetic　field　perturbations.　Our　result　not　only　mathematically　verifies　that　a　strong　impressed　magnetic　field　can　prevent　the　singularity　formation　of　classical　solutions　with　large　initial　data　in　the　viscous　MHD　case,　but　also　provides　a　starting　point　for　the　existence　theory　of　large　perturbation　solutions　to　the　3D　non-resistive　viscous　MHD　equations.　In　addition,　we　also　show　that　for　large　time　or　sufficiently　strong　impressed　magnetic　fields,　the　MHD　equations　converge　to　the　corresponding　linearized　pressureless　equations　in　the　algebraic　convergence-rates　with　respect　to　both　time　and　field　intensity.　©　2023,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH,　DE,　part　of　Springer　Nature.