Objective To detect the content of plasma ctDNA and the mutation rate of BRAF V600E in plasma of patients with thyroid carcinoma ,and to explore its clinical significance. Methods Plasma ctDNA was extracted from 16 patients with thyroid carcinoma and 59 patients with benign thyroid nodules by using the blood genomic DNA Extraction Kit. The ctDNA content was detected by fluorescence quantitative PCR ,and the mutation of circulating BRAF V600E was detected by PCR and sequencing. Then the clinical significance was analyzed by combined detection analysis. Results The content of ctDNA in thyroid cancer group was significantly higher than that in benign nodule group (P < 0.01). BRAF V600E mutation detection showed that the mutation rate was 43.75%,but benign nodules had no mutation. Parallel combined detection improved the sensitivity and the specific-ity of the combined detection was higher. Conclusion Combined detection of ctDNA and BRAF V600E in plasma is helpful for differential diagnosis of benign and malignant thyroid nodules.