Objective: To compare the diagnostic effect of ultrasound-guided 18-needle and 20-needle aspiration biopsy on thyroid nodules. Methods: A total of 167 patients with thyroid nodules admitted to the Department of Ultrasound in our hospital from 2018.8.6 to 2020.9.30 were selected as the research objects, and the patients were divided into 18-needle puncture group (n=86) and 20-needle puncture group (n=81), Apply ultrasound-guided 18-needle and 20-needle biopsy to the two groups of patients, respectively, to compare the incidence of uncertain results, including the undetermined significance of non-diagnostic or atypia/follicular lesions, and the diagnostic performance of malignant tumors. The final diagnosis is performed in the nodule. The incidence of complications and the yield of core needle biopsy specimens guided by ultrasound were compared between the two groups. Results: Comparing the clinical characteristics of patients in the 20-needle puncture group and the 18-needle puncture group, there was no significant difference in gender, age, nodule size, nodule shape, orientation, echo intensity, performance, and calcification between the two groups (P<0.05). ); 43 nodules in the 20-needle puncture group and 46 nodules in the 18-needle puncture group were finally diagnosed. The proportion of malignant nodules was not significantly different between the two groups. In the final diagnostic analysis, there were 38 nodules in the 20-needle puncture group and 40 nodules in the 18-needle puncture group. In the 20-needle puncture group, 38 nodules included 6 non-diagnostic results, 18 atypical/follicular lesions (significance not determined), and 14 follicular tumors. In the 18-needle puncture group, 40 nodules included 1 non-diagnostic result, 22 atypical/follicular lesions of undetermined significance, 17 follicular tumors.. [ABSTRACT FROM AUTHOR]