To search for the relationship between immune state and tumor metastases, CD3,CD4,CD8 and CD44 contents in 13 speciments of fine needle aspiration (FNA) from thyroid cancer patients were detected by the flowcytometry (FCM) and comparison between thyroid cancer and benign tumor was made. The result showed :in thyroid cancer group, CD＋3，CD＋4 cells and the ratio of CD＋4/CD＋8 reduced significantly (Ｐ＜0.01),and CD＋8 cell increased significantly (Ｐ＜0.01), in metastases group,this change was much significantly. CD44 expressed significantly higher in cancer group than that of the benign thyroid neoplasms, and the change was related to the tumor metastases. The results indicate that CD44 can be as a marker of tumor and indicator of metastases. The disturbance of immune system results in active expression of CD44 by tumor cells, so, lead to metastases. It is helpful to the diagnosis of thyroid cancer, assessment of metastases and management in surgery.