Objective To analyze the related factors of thyroid incidental cancer.Methods A total of 68 patients were selected.They were with preoperative definite or highly suspected adenocarcinoma of one side thyroid gland,while the lateral was without nodules or nodules were not suspected.They were received total thyroidectomy or lymphadenectomy of cervical lymph node in Department of General Surger-y,Jiangsu Traditional Chinese Medicine Hospital between 2016-07 and 2017-07.They were divided into incidental papillary carcinoma group and non-incidental papillary carcinoma group.The related factors of thyroid incidental cancer were analyzed. Results There were no statistically significant differences in gender(P=1.000),age(P=0.750),cervical lymph node enlargement(P=1.000),diameter of primary cancer nodule(P=0.910),diameter of primary carcinoma(P=0.660),the ratio of carcinoma and nodule (P=0.560)and lateral cervical lymph node metastasis(P=1.000)between the two groups.There were statistically significant differences in complicating with other carcinoma(P=0.038),Hashimoto's thyroidi-tis(P=0.013),increase of TSH(P=0.003),the location of primary carcinoma(P=0.038),multiple or single of primary carcinoma(P=0.014),infringement of coated(P=0.021)and center cervical lymph node metastasis(P=0.044).The analysis showed that the increase of TSH and multiple primary carcino-mas were the independent risk factors for IPC.There was significant difference between the two groups in diameter of the contralateral nodules(P=0.016).There was no significant difference in multiple or single of the contralateral nodules(P=1.000).Conclusion In the cases with preoperative definite or highly suspected adenocarcinoma of one side thyroid gland accompanied with increasing of TSH and multiple pri-mary carcinomas,an increased risk of incidental cancer in the lateral adenocarcinoma should be paid at-tention.