Objective:To investigate the expression of estrogen receptor alpha (ERα) protein and BRAF V600E protein in thyroid papillary carcinoma (PTC) and their relationship with clinical factors of PTC. Methods:The expression of ERα and BRAF V600E protein in 1 105 PTC patients was detected by immunohistochemistry. The relationship among ERα, BRAF V600E protein and clinical factors were analyzed. Results:Positive ERα protein was correlated with maleness (χ 2= 6.087, P=0.001), age< 45 years old (χ 2=5.197, P=0.023) and multifocal tumors (χ 2=4.446, P=0.035). Positive BRAF V600E protein was correlated with positive ERα protein (χ 2=6.209, P=0.013), Hashimoto thyroiditis (χ 2=29.388, P<0.001), no lateral lymph node metastasis (χ 2=6.849, P=0.009) and multifocal tumors (χ 2=9.596, P=0.035). Conclusions:ERα expression is more common in male patients, patients younger than 45 years of age, those with multifocal tumors and positive BRAF V600E protein. BRAF V600E protein may inhibit Hashimoto's thyroiditis, tumor growth and the occurrence of lateral lymph node metastasis, and promote the occurrence of multiple focal tumors.