OBJECTIVE: To explore the effect of the micro ribonucleic acid (miR)-223 on the thrombophlebitis rats by regulating the Toll-like receptor (TLR) signaling pathway. MATERIALS AND METHODS: The rat model of thrombophlebitis was established, and miR-223 was silenced or overexpressed through lentiviral transfection. The rats were divided into miR-223 inhibitors group (Inhibitors group), miR-223 mimics group (Mimics group), and normal group (Control group). The transfection efficiency of miR-223 in venous tissues was detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR), the hemorheological indexes plasma viscosity (PV) and hematocrit (HCT) were observed, and the content of the serum inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-β (TNF-β) were detected via enzyme-linked immunosorbent assay (ELISA). Moreover, the fibrinolytic indexes plasminogen activator inhibitor (PAI) and the tissue-type plasminogen activator (t-PA) were detected, the morphological changes in the venous tissues were observed via hematoxylin-eosin (HE) staining, and the gene and protein expressions of the TLR signaling pathway were detected via RT-PCR and Western blotting. RESULTS: The expression of miR-223 was significantly increased in the Mimics group (p<0.05) and significantly decreased in the Inhibitors group (p<0.05). The high-shear and low-shear whole blood viscosity and HCT in the Inhibitors group were significantly higher than those in the Mimics group (p<0.05). The levels of serum IL-6, IL-1β, and TNF-β in the Inhibitors group were remarkably higher than those in the Mimics group (p<0.05). The Inhibitors group had a remarkably lower level of t-PA (p<0.05) and a remarkably higher level of PAI than the Mimics group (p<0.05). Besides, the inferior vena cava wall shed and disappeared due to complete necrosis in the Inhibitors group. In the Mimics group, the vascular lumen was slightly expanded, and the vascular wall had intact contour. It was found in the gene detection that the mRNA levels of TLR2, myeloid differential protein-88 (MyD88) and c-Jun N-terminal kinase (JNK) were evidently increased in the Inhibitors group, and the significant increases in the protein levels of TLR2 and MyD88 were also observed in the protein detection. CONCLUSIONS: The overexpression of miR-223 can inhibit the TLR signaling pathway, thereby promoting the recovery of thrombophlebitis rats.