The　electromagnetic　fields　possessing　optical　chirality　are　very　important　to　circular　dichroism　(CD)　analysis　for　chiral　molecules.　Plasmonic　nanostructures　are　often　adopted　to　generate　the　chiral　near-fields　for　enhancing　the　weak　CD　signal　of　the　chiral　molecules,　which　is　called　plasmonic-enhanced　CD　spectroscopy.　However,　due　to　the　conservation　of　optical　chirality　the　general　nanostructures　cannot　provide　sign-uniform　chiral　near-fields　close　to　the　structures,　which　dramatically　reduce　the　performance　of　plasmonic-enhanced　CD　spectroscopy.　The　prerequisite　of　plasmonic-based　CD　analysis　is　to　generate　two　enantiomeric　chiral　fields　with　opposite　optical　chirality　close　to　the　nanostructures　in　two　independent　measurements.　Therefore,　the　design　that　can　provide　a　handedness-switchable　and　equivalent　optical　chirality　of　near-field　of　plasmonic　structure　is　desired.　In　this　paper,　we　show　that　simple　1D　periodic　metal　grooves　can　provide　handedness-switchable,　sign-uniform　chiral　fields　inside　the　grooves　with　enhanced　optical　chirality　through　adjusting　the　linear　polarization　direction　of　incident　light　from　+45°　to　-45°　off　the　periodic　direction.　A　reflection-type　plasmonic　CD　spectroscopy　scheme　was　proposed　based　on　metal　grooves,　which　works　under　illumination　of　linearly　polarized　light.　Moreover,　the　numerical　simulation　including　chiral　analytes　was　implemented　to　verify　the　feasibility.　The　proposed　CD　spectroscopy　scheme　has　the　potential　for　rapid　and　low-cost　chiroptical　sensing　for　a　small　quantity　of　chiral　molecules.　©　2017　IOP　Publishing　Ltd.