Objective To investigate the expression and significance of PDCD4 in thyroid papillary cancer (TPC). Methods  PDCD4 immunohistochemical expression was investigated in 62 cases of TPC, 20 cases of paracarcinomatous normal tissue and 28 cases of benign thyroid tumor. Their relationship with clinical data was analyzed. Result The positive rate of PDCD4 protein was significantly lower in TPC than that in paracarcinomatous normal tissue and benign thyroid tumor (P < 0.05). And with the decreasing of PDCD4 protein expression level, the malignant degree of TPC increased, which had statistically significant difference among groups (P < 0.05). But the expression of PDCD4 protein had no relationship to lymph node metastasis (P > 0.05). Conclusions The down-regulated expression of PDCD4 protein is correlated with the pathogenesis and development in TPC.