Abstract: Caenorhabditis elegans has become an important model organism for studying olfactory information processing because of its well-defined nervous system architecture, complete connectome, mature genetic tools, and readily quantifiable behavioral phenotypes. This review summarizes recent progress in peripheral odor detection and signal transduction, circuit integration and state-dependent regulation, behavioral decision-making, and translational research in the olfactory system of C. elegans. Particular emphasis is placed on the translational potential of studies on chemosensation and host recognition in plant-parasitic nematodes, while also addressing applications involving early functional indicators of neurodegenerative diseases and pathogen-related behavioral defense. Current evidence indicates that the C. elegans model facilitates the analysis of chemosensory organization from molecular, cellular, circuit, and behavioral levels. However, differences in receptor composition, circuit organization, and ecological context also limit the cross-species extrapolation of relevant mechanisms. Future studies should further examine conserved functional nodes and evaluate their potential applications in specific host or pathogen-related contexts.