In the high water cut development stage of oilfields，selective water shutoff technology is crucial for enhancing oil recovery. Emulsion-based water shutoff technology has emerged as a research and application hotspot due to its advantage of selective plugging. This paper systematically reviewed the mechanisms of selective water shutoff using emulsions，including core viscosity increase and mobility control，physical plugging and Jamin effect，and rock wettability alteration. The influences of various factors on emulsion stability，such as emulsifier type，pH value，temperature，salinity，and crude oil composition，were analyzed in detail. Traditional emulsion-based water shutoff systems （active heavy oil-based and emulsion-based） and their stabilization technologies were summarized and compared. Furthermore，novel heavy oil emulsion phase inversion water shutoff systems were introduced，and the phase inversion mechanisms and technical progress based on salinity and pH control were discussed.