Near-infrared　(NIR)　fluorescence　imaging　has　been　proved　as　an　effective　modality　in　identifying　the　tumor　border　and　distinguishing　the　tumor　cells　from　healthy　tissue　during　the　oncological　surgery.　Developing　NIR　fluorescent　probes　with　high　tumor　to　background　(T/B)　signal　is　essential　for　the　complete　debulking　of　the　tumor,　which　will　prolong　the　survival　rate　of　tumor　patients.　However,　the　nonspecific　binding　and　＂always-on＂　properties　of　the　conventional　fluorescent　probes　leads　to　high　background　signals　and　poor　specificity.　Method:　To　address　this　problem,　glutathione　(GSH)-responsive,　two　disulfide-bonded　dicyanine　dyes　(ss-diCy5　and　ss-diNH800CW)　were　synthesized.　As　synthesized　dyes　are　quenched　under　normal　physiological　conditions,　however,　once　reached　to　the　tumor　site,　these　dyes　are　capable　of　emitting　strong　fluorescence　signals　primarily　because　of　the　cleavage　of　the　disulfide　bond　in　the　tumor　microenvironment　with　high　GSH　concentration.　Besides,　the　GSH-responsive　behavior　of　these　dyes　was　monitored　using　the　UV-vis　and　fluorescence　spectroscopy.　The　diagnostic　accuracy　of　the　aforementioned　dyes　was　also　tested　both　in　tumor　cells　and　4T1-bearing　mice.　Results:　The　fluorescence　signal　intensity　of　disulfide　dicyanine　dyes　was　quenched　up　to　89%　compared　to　the　mono　cyanine　dyes,　thus　providing　a　very　low　fluorescence　background.　However,　when　the　disulfide　dicyanine　dye　reaches　the　tumor　site,　the　dicyanine　is　cleaved　by　GSH　into　two　mono-dyes　with　high　fluorescence　strength,　thus　producing　strong　fluorescent　signals　upon　excitation.　The　fluorescent　signal　of　the　dicyanine　was　enhanced　by　up　to　27-fold　after　interacting　with　the　GSH　solution.　In　vivo　xenografts　tumor　studies　further　revealed　that　the　fluorescence　signals　of　aforementioned　dyes　can　be　quickly　recovered　in　the　solid　tumor.　Conclusion:　In　summary,　the　disulfide　dicyanines　dyes　can　provide　a　promising　platform　for　specific　tumor-activatable　fluorescence　imaging　with　improved　T/B　value.