A new bi-directional horizontal spraying aerosol fire-extinguishing apparatus is disclosed, which comprises a shell structure, an aerosol generator including an aerosol generating agent and disposed inside the shell structure, and a control unit for initiating the aerosol generator. The bi-directional horizontal spraying aerosol fire-extinguishing apparatus of the present invention is characterized in that both ends of the shell structure or of the aerosol generator are respectively provided with an aerosol exhaust passage. The advantages of the present apparatus are in that it can reduce the spraying time of the aerosol extinguishing agent in the case of ensuring the fire-suppression efficiency, and increase the charge capacity of the fire-extinguishing apparatus, so that the capacity efficiency of the present apparatus is totally increased, and the present apparatus is easy and safe to be installed and does not occupy the useful space.