Objective To investigate the biological effects of NF-kappa B p65 (NF-κBp65) on nasopharyngeal carcinoma. Methods NF-κBp65 specific siRNA plasmid expression vector (pGPU6/RFP/Neo-NF-κB p65) and negative control plasmid expression vector (pGPU6/RFP/Neo-NC) were constructed and transfected into human nasopharyngeal carcinoma CNE2 cell line by non-liposomal lipid transfection agent to establish NF-κB p65 silencing stable transfected CNE2 cell line (NF-κB p65 silencing group) and negative control cell line (negative control group). The expression of NF-κB p65 gene in cancer cells was analyzed by Western blot. The proliferation and cell cycle of cancer cells were analyzed by MTT assay and Flow Cytometry. A xenograft model in nude mice was established to analyze the tumor igenicity of cancer cells. Results The stable transfected CNE2 cell lines were successfully obtained. The expression of NF-κB p65 protein was decreased in cells of NF-κB p65 silencing group. The cell cycle was arrested in S phase and proliferation was reduced after NF-κB p65 was silenced. The growth of transplanted tumor in nude mice of NF-κB p65 silencing group was slower, and weight of transplanted tumor was lighter than that in negative control group or blank control group, the difference was statistically significant (F = 14.386, P < 0.05). Conclusions Malignant biological phenotype of nasopharyngeal carcinoma CNE2 cell line could be reduced by silencing NF-κB p65.