Objective To analyze the correlation of serum high-sensitivity C-reactive protein (hs-CRP) level with metabolic syndrome (MS) and related metabolic diseases in the longevous people based on the Guangxi Natural longevity cohort. Methods A total of 265 longevous people aged 90 years and above living in Dongxing City and Shanglin County, Guangxi were enrolled during July to November 2019. Their demographic data, height, body mass, waist circumference, blood pressure, fasting blood glucose, blood lipids and hs-CRP levels were collected by house-to-house survey. The participants were divided into MS group (n=68) and non-MS group (n=197) according to whether they had MS or not, and also into hs-CRP ≥3 mg/L group (n=160) and hs-CRP <3 mg/L group (n=105) according to their hs-CRP levels. SPSS statistics 21.0 was used for data analysis. Student′s t test, Mann-Whitney U test, Chi-square test or Fisher exact test was employed for intergroup comparison, and multivariate logistic regression analysis was performed to analyze the relationship of hs-CRP with MS and its related metabolic diseases. Results The level of hs-CRP was significantly higher in the MS group than the non-MS group (P<0.05). The elderly with hs-CRP ≥3mg/L had higher ratios of hyper-low-density lipoprotein cholesterolemia, dyslipidemia and MS (P<0.05), and lower prevalence of hypertension than those from the non-MS group (P<0.05). They were also at risks of MS (OR=2.173,95%CI 1.151-4.106), dyslipidemia (OR=2.003,95%CI 1.128-3.555), hypertriglyceridemia (OR=2.139,95%CI 1.013-4.518), and hyper-low-density lipoprotein cholesterolemia (OR=3.821,95%CI 1.319-11.072), but at reduced risk of hypertension (OR=0.282,95%CI 0.087-0.908). Conclusion Serum hs-CRP level in longevous people are associated with MS, dyslipidemia, hypertriglyceridemia, hyper-low-density lipoprotein cholesterolemia and hypertension, and those with elevated hs-CRP are at increased risk of MS.