Flow　battery　electrodes　are　vital　for　performing　redox　reactions,　and　an　in-depth　understanding　of　reaction　kinetics　and　spatial　distribution　differences　in　electrodes　is　very　important　for　improving　the　efficiency　of　electrochemical　reactions.　In　this　study,　a　reflection-type　phase-sensitive　weak　measurement　imaging　system　was　developed　for　the　detection　of　flow　batteries.　The　phase　difference　between　two　polarization　components　in　total　internal　reflection　caused　by　electrode　redox　processes　was　measured　by　weak　value　amplification.　The　resulting　refractive　index　resolution　of　the　imaging　system　was　estimated　to　be　2.8-4.2　×　10-6RIU.　The　real-time　monitoring　ability　of　the　system　was　demonstrated　by　linear　sweep　voltammetry　tests　of　vanadium　redox　batteries.　Compared　to　traditional　optical　methods,　the　proposed　weak　measurement　imaging　sensor　did　not　require　coating,　as　it　can　be　used　in　acid　electrolytes　of　vanadium　flow　batteries.　Meanwhile,　the　weak　value　amplification　effect　led　to　a　higher　resolution　than　the　total　internal　reflection　system　shown　in　our　previous　work,　thereby　resulting　in　more　accurate　detection　of　electrochemical　reactions.　In　sum,　the　proposed　sensor　looks　very　promising　for　the　detection　of　electrochemical　reactions　in　flow　batteries,　water　splitting,　electrochemical　corrosion,　and　electrocatalysis.　©　2021　American　Chemical　Society