Numerical analysis was conducted to investigate flow and heat transfer characteristics in louver fin exchanger, which were influenced by louver pitch, fin pitch, louver angle and inlet velocity. Standard $k-varepsilon$ turbulent modelling was used in this study, and compared with laminar modelling. As a result of this study, Nusselt number became smaller as louver pitch or fin pitch was greater. Drag coefficient became smaller as louver pitch or fin pitch was greater, but it was little affected by inlet velocity.