Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with increasing incidence worldwide. Accumulating evidence indicated that circular RNAs (circRNAs) behave as a novel class of transcription products during multiple cancer processes. Specifically, hsa_circ_0001649 has been reported to be down-regulated in several cancers. However, its clinical significance and functional roles in PDAC is still unknown. RT-qPCR was carried out to measure the expression of hsa_circ_0001649 in PDAC tissue samples and cell lines. Additionally, the correlation between hsa_circ_0001649 expression and clinicopathological features was analyzed. The prognostic role of hsa_circ_0001649 was explored by Cox regression analysis. The potential effects of hsa_circ_0001649 in PDAC cells were evaluated in vitro including cell proliferation, colony-forming ability and apoptosis. As a result, hsa_circ_0001649 was abnormally decreased in PDAC tissues and cells, and this down-regulation was correlated with tumor stage and differentiation grade in PDAC patients. Hsa_circ_0001649 could serve as an independent prognostic factor for PDAC patients after surgery. What's more, increased hsa_circ_0001649 caused tumor suppressive effects via reducing cell proliferation, colony-forming ability and promoting cell apoptosis in PANC1 and BxPC3 cells. Collectively, the results illustrated that hsa_circ_0001649 may play a tumor suppressor role in PDAC and offer a potential therapeutic target for treating this fatal disease.