Abstract: Objective The expression levels of chemokine C-C-Motif Ligand 1(CCL1) and microRNA (miR) -21-5p in conjunctival epithelial cells and tears of patients with dry eye were detected to analyze their clinical significance.Methods A total of 118 patients with dry eye in Enshi Tujia and Miao Autonomous Prefecture Central Hospital were gathered as the dry eye group, and 92 healthy subjects were gathered as the control group. According to the severity of the disease, dry eye patients were divided into mild group (39 cases), moderate group (46 cases) and severe group (33 cases). Collect conjunctival epithelial cells and tears from two groups of subjects and detect the expression levels of CCL1 and miR-21-5p. Compare the expression levels of CCL1 and miR-21-5p, as well as the tear break-up time (BUT), tear secretion test (SIT), and corneal fluorescence staining (CFS) scores between the two groups. The correlation of CCL1 and miR-21-5p expression levels with SIT value, BUT value and CFS score was analyzed. The efficacy of CCL1 and miR-21-5p in the diagnosis of dry eye was analyzed by receiver operating characteristic curve (ROC).Results The expression levels of CCL1 and miR-21-5p in the conjunctival epithelial cells of the dry eye group were (353.26±70.45) ng/L, 1.67±0.38, which were obviously higher than those in the control group (263.16±49.27) ng/L, 1.01±0.12 (P<0.05); the expression levels of CCL1 and miR-21-5p in tears of the dry eye group were (265.29±55.90) ng/L, 1.45±0.28, which were obviously higher than those of the control group (189.71±32.56) ng/L, 0.98±0.13 (P<0.05). The SIT value and BUT value of the dry eye group were lower than control group, and the CFS score was higher than control group (P<0.05). The expression levels of CCL1 and miR-21-5p in conjunctival epithelial cells, tears and CFS score increased gradually, while the SIT value and BUT value decreased gradually in the mild, moderate and severe groups (P<0.05). Correlation analysis showed that CCL1 was positively correlated with the expression level of miR-21-5p in conjunctival epithelial cells and tear fluid (r=0.706, 0.752, P=0.000). Conjunctival epithelial cells and tears CCL1 and miR-21-5p were obviously inversely correlated with SIT value and BUT value, and directly correlated with CFS score (P<0.05). The values of CCL1, miR-21-5p, and CCL1 combined with miR-21-5p in conjunctival epithelial cells in the diagnosis of dry eye were 0.850, 0.869, and 0.937, respectively. The values of CCL1, miR-21-5p, and CCL1 combined with miR-21-5p in tear in the diagnosis of dry eye were 0.907, 0.881, and 0.964, respectively.Conclusions The expression levels of CCL1 and miR-21-5p in conjunctival epithelial cells and tears of patients with dry eye were increased, and CCL1 and miR-21-5p were related to the disease, SIT value, BUT value and CFS score. The combined detection of the expression levels of CCL1 and miR-21-5p in conjunctival epithelial cells or tears was helpful for the auxiliary diagnosis of dry eye.