Objective: To analyze the relationship between coagulation function indicators and serum anti-cyclic citrullinated peptide (anti-CCP) antibody levels in patients with newly diagnosed rheumatoid arthritis (RA) and different disease activities. Methods: The clinical data of 60 patients with active RA admitted to the hospital from June 2022 to June 2025 were reviewed. Based on the 28-joint Disease Activity Score (DAS28), the patients were divided into the low activity group (26 cases) and the medium/high activity group (34 cases). Clinical data and hematological indices [D-dimer (D-D), fibrinogen (FIB), thrombin time, prothrombin time, activated partial thromboplastin time, anti-CCP antibody, erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF)] of the two groups were compared. Logistic stepwise regression analysis was performed to identify the independent risk factors affecting disease activity in patients with RA. Spearman’s correlation was used to analyze the relationship between independent risk factors and disease activity in patients with RA. Plot receiver operating characteristic (ROC) curves and evaluate the diagnostic performance of each detection index for RA disease activity using the area under the curve (AUC). Results: The levels of D-D, FIB, anti-CCP antibody, ESR, and RF in the low activity group were lower than those in the medium/high activity group (P<0.05). Logistic regression analysis results showed that D-D and anti-CCP antibody levels were independent risk factors affecting disease activity in patients with RA (P<0.05). Spearman’s correlation analysis results showed that D-D and anti-CCP antibody levels were significantly positively correlated with moderate/high disease activity in patients with RA (P<0.05). ROC curve analysis results showed that the AUCs of D-D and anti-CCP antibody for diagnosing moderate/high activity of RA were 0.880 and 0.840, respectively. The AUC of combination (in parallel) of the two was 0.934 (95% CI: 0.839-0.982), with a sensitivity of 94.12% and a specificity of 88.46%. The AUC of combined diagnosis was larger than that of separate diagnosis (Z=2.384, 3.517, P<0.05). Conclusion: D-D and anti-CCP antibody levels are closely related to disease activity in patients with newly diagnosed RA. They can be used to diagnose moderate/high activity of RA, and combined detection can help improve diagnostic accuracy.