To evaluate the effectiveness of the number of central compartment lymph nodes (CLNs) on ultrasound (US) in predicting CLN metastasis (CLNM). We prospectively studied 309 papillary thyroid cancer (PTC) patients who underwent thyroidectomy with CLN dissection at our center from May 2017 to July 2017. The number and features of CLNs were evaluated preoperatively via US. All US examinations were performed using a Philips iU 22 or a GE Logiq 9 machine. Correlations between CLNs observed via preoperative US and amount of CLNM were evaluated. We found that >= 2 CLNs on the preoperative US was associated with CLNM (P<0.01). For this feature, the sensitivity, specificity, and area under the curve (AUC) were 54.3%, 66.1%, and 0.61, respectively. The presence of both suspected metastasis and >= 2 CLNs on US had a specificity of 86.5%. In addition, >= 3 CLNs on preoperative US was associated with large-volume CLNM (>5 metastatic CLNs) (P<0.01). For this feature, the sensitivity, specificity and AUC were 54.8%, 74.5% and 0.65, respectively. The presence of both suspected metastasis and >= 3 CLNs on US had a specificity of 84.9%. The presence of suspected metastasis and/or >= 3 CLNs had a sensitivity of 80.6%. Our results suggest that >= 2 and >= 3 CLNs on preoperative US may serve as ancillary preoperative markers for predicting CLNM.