With the advent of various detection technologies, the detection rate of thyroid nodules has increased significantly. Although most thyroid nodules are benign, the determination between benign and malignant lesions is still a challenge for clinicians. All patients with suspicious thyroid nodules should undergo neck ultrasound. Thyroid ultrasound can assess the characteristics of nodules, and some thyroid nodules have ultrasound signs of suspicious malignancy. However, these features lack accuracy and cannot clearly diagnose benign and malignant nodules. The current guidelines still recommend ultrasound-guided fine needle aspiration biopsy (FNAB) as the first choice for evaluating benign and malignant thyroid nodules. FNAB is a cost-effective diagnostic tool. Due to its small trauma, high sensitivity and specificity, it can be used to evaluate the nature of thyroid nodules before surgery and has become one of the indispensable clinical examination methods. In recent years, domestic reports about FNAB have been increasing. Domestic and foreign guidelines regarding FNAB indications are still controversial. At the same time, due to its own limitations, the full implementation of FNAB technology requires strict control of the indications and accurate interpretation of the pathological results of puncture. Although FNAB is the most commonly used diagnostic technique for preoperative evaluation of thyroid nodules, there are still gray area nodules that require further diagnostic studies. In order to formulate a reasonable surgical plan and judge the prognosis, the guidelines recommend that thyroid-stimulating hormone (TSH) levels can be measured before surgery. FNAB is a simple and relatively non-invasive technique, but it can also produce corresponding complications. The complications of FNAB are mainly related to the position of the thyroid nodule, the diameter of the puncture needle, and the operating experience of the puncture physician, of which, the severity is relatively light, and most are self-limiting. Scholars have been trying to find a new method to accurately diagnose thyroid cancer for atypical lesions or follicular lesions that cannot be diagnosed or whose meaning is not clear. Molecular biology methods are currently the best choice. Molecular biology methods confirm the malignancy of thyroid tumor biopsy by detecting driver mutations of specific thyroid tumor susceptibility genes, such as BRAF and RAS oncogene mutations, RET/PTC rearrangement and TERT mutation detection, thereby improving the efficiency of preoperative diagnosis. The most common metastatic site of papillary thyroid carcinoma is local lymph nodes. Although FNAB has diagnostic value for abnormal lymph nodes, small or cystic lymph nodes may not be diagnosed due to lack of tumor cells. Detection of thyroglobulin content in the washing fluid of fine needle aspiration biopsy of suspicious cervical lymph nodes can be used as an auxiliary means of cytological diagnosis. The author believes that the multi-level diagnostic system of FNAB combined with molecular biology can improve the accuracy of preoperative diagnosis and is of great value in guiding treatment and judging prognosis.