DNA　computing　has　become　the　focus　of　computing　research　due　to　its　excellent　parallel　processing　capability,　data　storage　capacity,　and　low　energy　consumption　characteristics.　DNA　computational　units　can　be　precisely　programmed　through　the　sequence　specificity　and　base　pair　principle.　Then,　computational　units　can　be　cascaded　and　integrated　to　form　large　DNA　computing　systems.　Among　them,　DNA　strand　displacement　(DSD)　is　the　simplest　but　most　efficient　method　for　constructing　DNA　computing　systems.　The　inputs　and　outputs　of　DSD　are　signal　strands　that　can　be　transferred　to　the　next　unit.　DSD　has　been　used　to　construct　logic　gates,　integrated　circuits,　artificial　neural　networks,　etc.　This　review　introduced　the　recent　development　of　DSD-based　computational　systems　and　their　applications.　Some　DSD-related　tools　and　issues　are　also　discussed.