The significance of hydrogen sulfide (H 2 S) as a crucial gasotransmitter has been shown extensively in plants, and endogenous H 2 S is often modulated to activate H 2 S signaling when plants respond to numerous developmental and environmental cues. Consequently, elucidating the H 2 S physiological concentrations and the H 2 S generation intensity of plants is key to understanding the activation mechanism of H 2 S signaling, which has attracted increasing attention. Currently, a variety of reaction-based methods have been reported for monitoring H 2 S concentration in vivo and in vitro. In this review, we summarize and describe in detail several methods for quantifying and bioimaging endogenous H 2 S in plants systems, mainly the spectrophotometer-dependent methylene blue (MB) method and fluorescence probes, including the reaction mechanisms, design strategies, response principles, and application details. Moreover, we also summarize the advantages and disadvantages of these methods as well as the research scenarios in which they are applicable. We expect that this review will provide some guidelines on the selection of methods for H 2 S sensing and the comprehensive investigations into H 2 S signaling in plants.