Objective: to evaluate the value of ultrasonographic observation of vocal cord movement in the diagnosis of vocal cord paralysis. Methods: Thirty five cases of thyroid cancer accompanied by hoarseness confirmed by biopsy or surgery in our hospital were enrolled in this study. All the patients were examined ultrasonography and laryngoscope. The passive and active movements of vocal cord and arytenoid cartilage were observed by ultrasonography. The movements were categorized into grades 1~3 (grade 1 was regarded as normal while ≥ grade 2 as paralysis). The evaluation criterion for laryngoscope was similar. The difference between the two methods was statistically analyzed, and the receiver operating curve (ROC) for ultrasonogrpahy was drawn and area under curve (AUC), sensitivity, specificity, positive predictive value, negative positive value, Youden index and diagnose accordance rate were calculated. Results: Among 35 patients, the grading of vocal cord movements by ultrasonography and laryngoscope was the same: 5 cases in grade 1, 17 cases in grade 2 and 13 cases in grade 3, without significant difference between them (X2 = 0.000, P = 1.000). AUC of ROC for ultrasonographic diagnosis of vocal cord paralysis was 0.883 (P = 0.007). The sensitivity, specificity, positive predictive rate, negative predictive rate, Youden index and diagnose accordance rate were 96.67%, 80%, 96.67%, 80%, 0.77 and 94.29, respectively. Conclusion: Ultrasonography has a high value in the diagnosis of vocal cord paralysis and can be used to the presurgical evaluation of the invasion of thyroid cancer to the recurrent laryngeal nerve.