Background: Gastric cancer is one of the most common gastrointestinal tumors. Evidence has pointed to the fact that miRNAs play critical roles in the occurrence, development, and metastasis of gastric cancer by regulating cell proliferation, differentiation, apoptosis, and invasion. Methods: In this study, first the relationship of miR-873-5p level and tissues types/LN(+/-)/metastasis(+/-)/ tumor size was analysis, respectively. Second, the CCK8 and Transwell assay was used to determine the proliferation, invasion and migration of GC cells transfected with overexpression-/low expressionmiR-873-5p. Third, the cell viability were analysis in the GC cells transfected with overexpression-/low expression-miR-873-5p treatment with different chemotherapy drugs. Fourth, the target gene of miR-8735p was predicted using bioinformation methods. Fifth, the relationship of miR-873-5p with target geneTHUMPD1 were explored by using Wb and luciferase activity assay, et al. Results: We confirmed that miR-873-5p was negatively correlated with GC including tumor size, LN metastasis, distant metastasis. The miR-873-5p enhanced the sensitivity of Doxorubicin/Fluorouracil and cisplatin. The THUMPD1 was the target gene of miR-873-5p. Moreover, miR-873-5p could target the THUMPD1 axis so as to inhibit gastric cancer cell behavior as well as chemoresistance. Conclusions: MiR-873-5p plays a role in regulating cell behavior as well as regulating chemoresistance in gastric cancer. In addition, THUMPD1, as a downstream molecule of miR-873-5p, plays an important role in the cell behavior and chemoresistance of gastric cancer. The research first confirmed that miR-873-5p could inhibit gastric cancer cell behavior and chemoresistance by targeting the THUMPD1.