Recent research on Gut-Brain Axis (GBA) has suggested that the gut luminal environment, including the dietary components and commensal microbiota, could affect behavior, emotion, and cognitive abilities in the brain. The research on GBA has heavily relied on animal models, which makes the research challenging. Recent advances in organ-on-a-chip technology could be a solution for GBA research. In present work, we developed a modular microfluidic chip, where gut epithelial and brain endothelial cells were co-cultured to form the gut epithelial barrier and the Blood-Brain Barrier (BBB). Cell responses to microbial byproducts were examined by TEER measurement for each barrier, and we observed the transport of fluorescently labeled exosome across the gut barrier towards the BBB. Our results suggest this model can be used as a novel in vitro model of GBA for studying the interaction between the gut and the brain.