To investigate paraffin section thickness in immunohistochemical detection of p16 expression in cervical tissue samples. p16 immunohistochemical staining was performed in 150 cases of chronic cervicitis, 126 cases of low-grade squamous intraepithelial lesions(LSIL), 96 cases of high-grade squamous intraepithelial lesions (HSIL) and 78 cases of cervical cancer from January 2014 to March 2018 in Zhongshan Boai Hospital. The results of p16 protein expression in paraffin sections with thickness of 2, 3, 4, 5 and 6 μm were compared using Logistic regression analysis. With the increase of slice thickness, the staining of p16 protein in nucleus gradually increased. The thickness of cervical slices in chronic cervicitis and cervical cancer samples had no significant effect on the positive rate of p16 protein(χ2=7.817 and 1.332, both P>0.05), while the thickness of slices in LSIL and HSIL samples had significant effect on the positive rate of p16 protein (χ2=17.688 and 10.182, P<0.05 or P<0.01). The stable and reliable results were obtained when the slices were between 3 and 5 μm thick. Paraffin sections with thickness of 3.0-5.0 μm are recommended for immnohistochemical staining of p16 protein in cervical tissue samples.