Objective To investigate the efficacy of ultrasound-guided cervical plexus block in radiofrequency ablation of thyroid and parathyroid benign lesions . Methods One hundred and twenty-five patients with thyroid nodules or hyperparathyroidism , who were undergone ultrasound guided radiofrequency ablation ,were randomly assigned to receive either ultrasound-guided cervical plexus block or local infiltration anesthesia ,and the pain grading was evaluated by numerical rating scale ( NRS ) . The anesthetic dosage and the effect of thermal ablation surgery of ultrasound-guided cervical plexus block anesthesia and local anesthesia were compared . Results The anesthetic dosage in ultrasound-guided cervical plexus block was lower than that in local infiltration anesthesia( t = 17 .681 , P < 0 .05) . The pain grading of ultrasound-guided cervical plexus block was lower than that of local infiltration anesthesia( χ2 = 33 .738 , P < 0 .05) . Conclusions Ultrasound-guided cervical plexus nerve block has lower anesthetic dosage and pain grading in the radiofrequency ablation of thyroid and parathyroid benign lesions ,which may be widely applied in clinical .