In　this　paper,　we　investigate　the　global　well-posedness　of　three-dimensional　Navier-Stokes　equations　with　horizontal　viscosity　under　a　special　symmetric　structure:　helical　symmetry.　More　precisely,　by　a　revised　Ladyzhenskaya-type　inequality　and　utilizing　the　behavior　of　helical　flows,　we　prove　the　global　existence　and　uniqueness　of　weak　and　strong　solutions　to　the　three-dimensional　helical　flows.　Our　result　reveals　that　for　the　issue　of　global　well-posedness　of　the　viscous　helical　flows,　the　horizontal　viscosity　plays　the　important　role.　To　some　extent,　our　work　can　be　seen　as　a　generalization　of　the　result　by　Mahalov　et　al.　(Arch　Ration　Mech　Anal　112(3):　193-222,　1990).