Objective To explore the value of TSH level and abnormal ultrasound features in the diagnosis of thyroid micro-nodules. Methods The concentration of TSH and the abnormal ultrasound features in 258 patients with 361 thyroid micro-nodules (the maximum diameter ≤ 1cm) which confirmed by fine needle aspiration or post-surgical histopathology were retrospectively analyzed. Results The malignant transformation rate of thyroid micro-nodules increased with the increase of TSH level. The micro calcification in abnormal ultrasound features had the highest positive predictive value, the second was ill-defined border. The TSH level (>4.95mIU/L), micro calcification and ill-defined border had similar specificity in the diagnosis of thyroid micro-nodules, but the sensitivity of TSH level and abnormal ultrasound features were lower. The combined detection TSH (>4.95mIU/L) level and abnormal ultrasound features (micro calcification or ill-defined border) could significantly improve the diagnostic sensitivity. Conclusion The preoperative TSH (>4.95mIU/L) could be used as an indicator in the diagnosis of malignant thyroid micro-nodules. The combined detection of TSH (>4.95mIU/L) level and abnormal ultrasound features (micro calcification or ill-defined border) might significantly improve the diagnostic accuracy.