Gemcitabine (GEM)-based chemotherapy is a commonly used treatment for pancreatic cancer. However, acquired drug resistance, a major problem in pancreatic cancer treatment, causes a reduction in the survival rate of patients with cancer. In this study, we attempted to reveal the molecular mechanism of GEM resistance. Our data showed that GEM treatment inhibits cell growth, induces apoptosis, and activates autophagy via the AMP-activated protein kinase (AMPK) pathway. The combination of GEM treatment and AMPK knockdown resulted in a dramatic increase of apoptosis and inhibition of autophagy. Additionally, inhibition of mammalian target of Rapamycin induced autophagy. Our findings show the potential therapeutic implications of the combined treatment with GEM and AMPK inhibitors for pancreatic cancer.