The invention relates to a multifunctional composite froth suppressing and recovering device used in biological fermentation. The invention is characterized in that the device comprises a novel foam suppressor, an exhaust internal drainage gas tray, a tank gas-liquid separation recoverer, a double L pipe and a recovered gas-liquid dispersing station, wherein, the devices are supported and communicated with one another in application, comprehensively solve three-high problems generally existed in the process of biological fermentation, namely the 'high froth' which affects yield, the 'high ventilation volume' which affects environment and the 'high energy consumption' which affects efficiency. When the device is matched with a bioreactor to use in fermenting production, overflow and liquid escape of a froth layer can be effectively prevented, and liquid loading volume and tank laying yield of fermentation liquid can be improved; meanwhile, environmental pollution is prevented, and obvious effects of energy economization and emission reduction are performed.