Abstract: Objective To investigate the relationship between the plasma level of microRNA-510 （miR-510） and efficacy of oxaliplatin-based chemotherapy in advanced gastric cancer. Methods Peripheral blood samples from 112 advanced gastric cancer patients treated with oxaliplatin-based chemotherapy were collected in our hospital. The level of miR-510 was measured by real-time quantitative PCR. The RECIST 1.1 was employed to evaluate the short-term efficacy of oxaliplatin-based chemotherapy in patients after 2 cycles. The patients of CR and PR were assigned as the sensitive group， while those of SD and PD were not sensitive group. The relationship between the sensitivity of chemotherapy and the plasma level of miR-510 were analyzed. The long-term survival of different plasma miR-510 levels were compared according to the follow-up data. In the same period， 94 peripheral blood samples from the hospital’s health examination were selected as control group. Results The relative levels of plasma miR-510 was 3.417±0.574 in patients with gastric cancer， higher than the control group（P＜0.05）. The expression of miR-510 in the plasma of patients with gastric cancer was related to TNM stage， degree of differentiation， lymph node metastasis and CEA level（P＜0.05）. Of the 112 patients with advanced gastric cancer patients after 2 cycles of chemotherapy， there were 48 cases of PR， 37 cases of SD and 27 cases of PD. The plasma level of miR-510 in 48 patients with chemotherapy sensitivity was 2.362±0.534， less than 4.208±0.602 of the patients who were not sensitive to chemotherapy （P＜0.05）. In the whole group， the median progression-free survival （PFS） and overall survival （OS） were 7.6 months and 11.5 months， respectively. The patients were divided into miR-510 high-level group and low-level group according to the median value of 3.053. The median PFS and OS were 5.3 and 10.2 months of miR-510 high-level group， less than 8.4 and 12.4 months of miR-510 low-level group （P＜0.05）. Conclusion The plasma miR-510 levels were elevated in the patients with gastric cancer， and associated with the sensitivity of oxaliplatin in advanced gastric cancer. The patients with higher miR-510 level had a poor prognosis， which has a value for predicting the effect and prognosis of patients with advanced gastric cancer treated with oxaliplatin.