This paper described the physicochemical characterization and application of quantum dots (CdSe/ZnS, QDs) whose surface were hydrophilic modified by mercaptoundecanoic acid (MUA). The stability kinetics of MUA-coated QDs (MUA-QDs) in aqueous solution was studied as a function of MUA-QDs concentration, type of light exposed, pH conditions and temperatures. The results show that the optimum concentration range of MUA-QDs is 0.5 to 1 mg/mL. We found that no obvious difference of fluorescence intensity was detected in MUA-QDs stored respectively at 4°C, 24°C and 44°C (8-hour). When they were exposed to UV light (312 nm) for 8 hr, their fluorescence intensity was shown serious decay. Moreover, the results showed that the pH of maximum stability of MUA-QDs in buffer solutions was 8. Finally, MUA-QDs had been endocytosis into H9c2 cells, a permanent cell line derived from rat cardiac tissue, for cell imaging application, the results provided the benefit to apply MUA-QDs in medical areas.