Objective To investigate the correlation between blood pressure and thickness of retinal nerve fiber layer (RNFL) in type 2 diabetes mellitus (T2DM). Methods A total of 123 patients with T2DM were selected for the study, who visited the Endocrinology Department of the First Hospital Affiliated to Harbin Medical University between January 2017 and December 2018. Based on the fluorescein fundus angiographic findings, the patients were divided into a group without diabetic retinopathy (NDR group, n=65) and a group with non-proliferative diabetic retinopathy (NPDR group, n=58) according to the International Clinical Grading Scale for Diabetic Retinopathy (2002). The general clinical data of the enrolled patients were collected, and the results of the blood tests, such as glycated hemoglobin A1c (HbA1c) and fasting C-peptide, were recorded. Systolic blood pressure (SBP), diastolic blood pressure (DBP) were measured, and mean arterial pressure (MAP) was calculated. RNFL thickness was measured with optical coherence tomography (OCT). SPSS statistics 22.0 was used for statistical analysis. The correlation between RNFL thickness and blood pressure in each quadrant was analyzed by Spearman rank correlation. Univariate and multivariate linear regression were performed to analyze the independent factors of RNFL thickness in each quadrant. Results SBP and MAP were significantly higher in the NPDR group than those in the NDR group (P<0.05). Correlation analysis revealed significantly negative correlation between age and RNFL thickness in both the supratemporal (r=-0.184, P=0.041) and infratemporal (r=-0.224, P=0.013) quadrants, between the body mass index (BMI) and the lower nasal retina (r=-0.256, P=0.004), between SBP and RNFL thickness in the upper nasal (r=-0.203, P=0.024), infratemporal (r=-0.272, P=0.002) and temporal (r=-0.286, P=0.001) quadrants, between MAP and RNFL thickness of the upper nasal (r=-0.185, P=0.041), infratemporal (r=-0.264, P=0.003) and temporal (r=-0.253, P=0.005) quadrants, and between HbA1c and RNFL thickness of the supratemporal (r=-0.234, P=0.009) and infratemporal (r=-0.201, P=0.025) quadrants, the difference being statistically significant for all (P<0.05). The univariate and multivariate linear regression analysis showed SBP as an independent factor of RNFL thickness in the upper nasal, infratemporal, and temporal quadrants. Conclusion Elevated blood pressure accelerates degenerative change in the retina, suggesting early attention to changes in blood pressure may help to avoid early nervous degeneration of the retina.