The aim of the present study is to investigate the role of RNA interference in the inhibition of MUC1 gene expression in occurrence and metastasis of oral squamous cell carcinoma (OSCC) and its in-depth mechanisms. The OSCC and normal oral mucosa tissues, as well as normal oral epithelial cell line HOK and OSCC cell line SCC-4, Cal-27, TSCCA, Tca8113 were obtained to detect the expression of MUC1. Slug expression in OSCC and normal oral mucosa tissues was also determined. The OSCC cells were grouped to investigate the role of MUC1 gene silencing on proliferation, DNA replication, cell cycle distribution, apoptosis, colony formation ability, epithelial-mesenchymal transition (EMT), invasion, and migration of OSCC cells. We first found higher positive rate of MUC1 and Slug expression in OSCC tissues. Next, it was determined that higher expression of MUC1 was found in OSCC tissues and cells. Furthermore, silencing of MUC1 declined Slug expression, inhibited the proliferation, DNA replication, cell cycle progression, and EMT while inducing apoptosis of OSCC cells. Our study suggests that overexpression of MUC1 is found in OSCC, and MUC1 gene silencing could inhibit the proliferation, invasion, and migration while inducing apoptosis of OSCC cells.