Abstract: Objective To explore the expression and clinical significance of circular RNA-UBAP2（ubiquitin associated protein 2） and UBAP2 protein in gastric cancer tissues and peripheral blood of patients with gastric cancer. Methods Selected 100 gastric cancer patients who underwent surgical treatment in our hospital from February 2019 to February 2020 to be included in the study. Collect peripheral blood, gastric cancer tissues and adjacent tissues of gastric cancer patients and normal people after surgery as samples, and use qRT-PCR to detect samples' cyclic RNA-UBAP2 expression in tissues, and analyzed its relationship with the clinical characteristics of patients. Western blot technology was used to detect the expression of UBAP2 protein in gastric cancer tissues and adjacent tissues. Results The relative expression of circular RNA-UBAP2 in gastric cancer tissues was （8.73±1.04）, significantly higher than that of adjacent tissues （5.12±0.85）, （P<0.001）; The relative expression of cyclic RNA-UBAP2 was （7.55±0.65）, which was significantly higher than that of normal human peripheral blood （5.08±0.23）, （P<0.001）; the expression of circular RNA-UBAP2 in gastric cancer lymph node metastasis, clinical stage, depth of invasion, distal metastasis and vascular tumor thrombus were related （P<0.05）; the area under the curve for the diagnosis of gastric cancer by circular RNA-UBAP2 was 0.813 （95%CI 0.729~0.934）, Youden index was 0.406, the diagnostic specificity was 82.15%, and the sensitivity was 91.10%; the expression of UBAP2 protein in gastric cancer tissue was significantly higher than that in adjacent tissues. Conclusions Circular RNA-UBAP2 was highly expressed in gastric cancer tissues and in the peripheral blood of patients with gastric cancer, and UBAP2 protein was also highly expressed in gastric cancer tissues, which may become a new index for clinical diagnosis of gastric cancer.