Objective To investigate the relationship between circKIF4A expression and clinicopathologic features and prognosis of thyroid cancer patients.Methods A total of 120 patients diagnosed with thyroid cancer in our hospital from April 2016 to April 2017 were selected by random sampling method.Cancer tissues and adjacent tissues were taken during surgery and divided into thyroid cancer group and adjacent cancer group according to surgical pathologic detection.The relative expression level of circKIF4A in thyroid cancer group and paracancer group was detected by qRT-PCR,and the relationship between circKIF4A expression and clini-copathological features of thyroid cancer was analyzed.Kaplan-Meier survival curve was used to analyze the relationship between circKIF4A expression and prognosis of thyroid cancer patients.Cox regression analysis was performed to analyze the factors influencing the poor prognosis of patients with thyroid cancer 5 years af-ter surgery.Results The relative expression level of circKIF4A in thyroid cancer group was higher than that in paracancer group,and the difference was statistically significant(P＜0.05).The expression of circKIF4A was correlated with the degree of capsule invasion,lymph node metastasis and differentiation(P＜0.05).Kap-lan-Meier survival curve analysis showed that the 5-year cumulative survival rate of patients with high cir-cKIF4A expression was lower than those with low circKIF4A expression,and the difference was statistically significant(x2=11.368,P=0.001).Multivariate analysis showed that envelope invasion,degree of differenti-ation,lymph node metastasis and circKIF4A expression level were the influencing factors for poor prognosis of thyroid cancer patients at 5 years after surgery(P＜0.05).Conclusion circKIF4A is highly expressed in thy-roid cancer tissues,which is related to the clinicopathological features and 5-year postoperative survival of thy-roid cancer patients,and may be used as a potential prognostic marker for thyroid cancer.