Abstract: This paper aimed to explore the umami characteristic of proline dipeptides in fish sauce. The STC-1 cells taste sensing model was established based on sensory evaluation in this study. Calcium imaging was used to reflect the taste dose effect of proline dipeptides. In order to identify the main receptors that mediate umami taste of proline dipeptides, effects on the mRNA expression of umami receptors (T1R1, T1R3, CaSR and GPRC6a) that dipeptides caused were measured by real-time quantitative PCR. The results showed that none of the 13 proline dipeptides had bitter taste, and most of them presented umami and sour taste. The dipeptides with stronger taste also had lower threshold values, among which the peptides with excellent taste activity were Ser-Pro, Ala-Pro, Pro-Ala, Pro-Val and Pro-Ile. The proline dipeptides with stronger taste activity had stronger upregulation effect on expression of umami taste receptors mRNA, and T1R1 was likely to be an important receptor mediating the umami taste of proline dipeptides. This study would provide a non-artificial sensory evaluation method for evaluating umami taste of proline dipeptides in fish sauce, and laid a foundation for further study of quantitative structure-activity relationship of umami oligopeptides in fish sauce.