The invention relates to a method for producing butanol-acetone through fermentation, in particular to an energy-saving environment-friendly butanol-acetone production method. Cassava is taken as raw material, zymogen is a clostridium butanol-acetone strain, the cassava is crushed, mixed, steamed and boiled, fermented, distilled, and rectified to obtain acetone, butanol and a byproduct alcohol, and the distillation step adopts a twin-tower multi-effect distillation method. The method greatly reduces production energy consumption, saves production cost, and ensures that the whole production process is more environment-friendly and energy-saving.