Objective <p>Capsular invasion in papillary thyroid cancer(PTC) refers to thyroid cancer penetrating the capsule without attaching to the surrounding tissue. Patients with and without capsular invasion may differ in the likelihood of lymph node metastasis(LNM). The purpose of this study is to study the relationship between circulating tumor cells(CTCs) and LNM in PTC with or without capsular invasion.</p> Methods <p>The clinical records of patients (age, gender, CTCs, thyroid function, Hashimoto’s thyroiditis, lesions number, lesions diameter, capsular invasion, clinical stage, and LNM) were analyzed retrospectively. The relationship between CTCs level and LNM was analyzed. Logistic regression analyses were used to evaluate the relationship between CTCs and LNM after adjusting for confounding factors.</p> Results <p>A total of 746 PTC patients were included, and 320 patients with capsular invasion and 426 without. The patients with capsular invasion had higher proportions of multifocality, maximum lesion diameter &gt; 1&#xa0;cm, T3-T4 stage, and LNM than patients without (all <i>p</i> &lt; 0.05). In multivariate logistic regression analyses, maximum lesion diameter &gt; 1&#xa0;cm (odds ratio(OR): 4.108, 95% confidence interval(CI): 2.459–6.862, <i>p</i> &lt; 0.001) was associated with LNM in patients without capsular invasion; positive preoperative CTCs levels (OR: 1.705, 95% CI: 1.023–2.842, <i>p</i> = 0.041), multifocality (OR: 2.811, 95% CI: 1.669–4.736, <i>p</i> &lt; 0.001), and maximum lesion diameter &gt; 1&#xa0;cm (OR: 3.233, 95% CI: 1.884–5.546, <i>p</i> &lt; 0.001) were associated with LNM in patients with capsular invasion.</p> Conclusions <p>Maximum lesion diameter &gt; 1&#xa0;cm was associated with LNM in PTC patients with and without capsular invasion. Positive preoperative CTCs levels and multifocality were associated with LNM in patients with capsular invasion, but not in patients without capsular invasion.</p>