Low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (LDL-C/HDL-C) ratio may carry additional information and has been suggested as a better predictor for atherosclerosis progression and cardiovascular disease (CVD) than LDL-C and HDL-C alone. Therefore, we aim to explore the association between LDL-C/HDL-C ratio and high carotid intima-media thickness (CIMT) risk in a large Cohort in Beijing, China. This cohort study included 13,612 adults without high CIMT at first entry and who attended the baseline examination and at least one follow-up annual examination between 2009 and 2016. We used multivariable Cox regression to estimate hazard ratios (HR) with their 95% confidence intervals (CI) for the association between LDL-C/HDL-C ratio and risk of high CIMT. During 37,912 person-years of follow-up, 1996 (1268 men and 728 women) developed high CIMT. Compared with the first quartile of LDL-C/HDL-C ratio, the risk of high CIMT was significantly increased for the fourth quartile of LDL-C/HDL-C ratio (HR = 1.51, 95% CI: 1.29-1.78). We observed a significant association between LDL-C/HDL-C ratio and high CIMT risk comparing LDL-C/HDL-C ratio >2.78 with LDL-C/HDL-C ratio ≤2.78 and significant dose-response relationship between LDL-C/HDL-C ratio and risk of high CIMT. The restricted cubic spline showed a significant nonlinear association between LDL-C/HDL-C ratio and the risk of high CIMT (pnon-linearity = 0.009). We identify a significant association between LDL-C/HDL-C ratio and the risk of high CIMT in the Chinese Cohort study. Future studies are needed to evaluate the effectiveness of reducing LDL-C/HDL-C ratio treatment on the development of high CIMT.