Background: To compare the necessity between Fine-needle aspiration (FNA) biopsy and ultrasound examination in the diagnosis of different sizes of the thyroid nodules. Does the FNA biopsy have to do it all? Methods: A retrospective analysis was performed to 8352 thyroid patients who underwent thyroid operations between 2011 and 2016 in our hospital. Results: In FNA(+) group, the nodule was more smaller, the increment speed of the amount of operation increased more faster. In no FNA group, the increment speed decreased not obvious in nodules ≥10mm sub-group, but tremendous in both nodules 5mm-10mm sub-group and nodules ≤ 5mm sub-group no matter the nodules were malignant or benign. Over the six years, the total operation number increased, but operation of patients with nodules ≥10mm decreased slightly and operation of patients with nodules <10mm increased markedly especially in nodules ≤ 5mm sub-group. In no FNA group, to compare the malignancy or benign tumor after surgery between nodules 5mm-10mm sub-group and nodules ≥10mm sub-group, χ2=12.000,P=0.001, and between nodules ≤ 5mm sub-group and nodules ≥10mm sub-group, χ2=7.968,P=0.005, but between nodules 5mm-10mm sub-group and nodules ≤ 5mm sub-group, χ2=0.669,P=0.414. Further pairwise comparison showed, in nodules 5mm-10mm sub-group and nodules ≤ 5mm sub-group, the probability of benign tumor was greater than nodules ≥10mm sub-group. Conclusions: In thyroid nodules ≥10mm sub-group, there is no statistical difference between ultrasound diagnosis and biopsy. In nodules <10mm sub-groups, FNA biopsy has the great significance in the diagnosis to add more references for the subsequent treatment.