Condensed and gaseous phase flame-retardant mechanisms are two typical intrinsic modes of actions for the flame retardation of polymeric materials. However, most of the flame retardants only show one of the flame-retardant mechanisms. Some typical flame retardants which acted in condensed or gaseous phase are synthesized in the present study. Furthermore, those substances are used to prepare flame-retardant systems acting both in condensed phase and in gaseous phase for the flame-retardant modification of PA6, PBT, ABS and other polymers. How to reduce the loadings of flame retardants and to enhance the flame-retardant efficiency of the systems are discussed according to the flame-retardant mechanisms, especially to the combination of flame-retardant modes in condensed phase and gaseous phase.