Background Thyroid cancer is the most common neck malignancies which accounts for 1% of all malignancies and 4% of thyroid diseases. Its incidence rate is increasing year by year. It is more frequent in women. Most thyroid cancer is well differentiated and lower malignant. Surgery is the main effective treatment. Because of the lack of specific symptoms and coexisting with benign thyroid disease, the preoperative diagnosis rate is low. And these patients often are re-operated because of misdiagnosis and mistreatment. We will discuss the causes of misdiagnosis of thyroid cancer, countermeasures and reoperation in this article. Methods Analysis misdiagnosed causes of 77 cases of thyroid cancer and the effect of reoperation. Results 77 cases were diagnosed only according to preoperative physical, ultrasound and laboratory tests. 71 cases outsides of our hospital were caused misdiagnosis because of initial surgery without frozen section; 6 cases misdiagnosed by our hospital, In these 2 cases without the frozen section, 2 cases with frozen sections misdiagnosed as benign adenomas and 2 cases could not give qualitative diagnosis. All 77 cases were done a repeat operation. The residual cancer diagnosis coincidence rate that we calculated was 71.4% before reoperation. After reoperation, pathology confirmed 35 cases remained thyroid cancer, residual cancer rate is 45.45%; Preoperative clinical examination show lymph node metastasis coincidence rate is 80%; 60 cases underwent routine central area or regional selective and modified neck lymph node dissection. 40 patients were pathologically confirmed lymph node metastasis. 3 cases had transient hypocalcemia. From reoperation to the last follow-up the time was 3 to 41 months. No case had cancer recurrence, complications and death. Conclusions Single preoperative diagnosis method and no intra-operative frozen section are the mam reasons for misdiagnosis. The patients of misdiagnosed thyroid cancer should be given reoperation ti- ely. According to the individual condition, we can choose a reasonable surgical method and the reoperation effect is satisfactory.