Objective: To evaluate the effects of miR-21/PARP-1 of peripheral blood on allergic rhinitis (AR) and combined allergic rhinitis and asthma syndrome (CARAS). Methods: Peripheral blood was collected from 44 patients with CARAS, 31 patients with AR and 42 healthy controls. The expression level of miR-21 in peripheral blood was detected by real-time fluorescence quantitative PCR and the level of PARP-1 protein in plasma was detected by ELISA. Correlation analysis was performed by Pearson correlation analysis. The diagnostic sensitivity and specificity of miR-21 and PARP-1 were determined by ROC curve. Results: The expression of miR-21 in AR and CARAS patients was higher than that in control group. The PARP-1 concentration in CARAS patients was lower than that in AR and control groups. Correlation analysis showed that miR-21 was correlated with eosinophils in AR patients and FnNO in CARAS patients. PARP-1 was associated with FEV1/FVC in patients with AR, and with FEV1%pre in patients with CARAS. ROC curve analysis showed that miR-21 could be used as a diagnostic marker for AR, and PARP-1 could be used as a diagnostic marker for AR progression to CARAS. Conclusion: There is differential expression of miR-21/PARP-1 in peripheral blood of patients with AR and CARAS. miR-21 can be used as a diagnostic marker for AR and CARAS, and PARP-1 can be used as a biomarker for AR progression. It is of great value to seek the diagnosis and treatment targets of AR and CARAS.