The invention discloses a method for producing butyl alcohol and succinic acid through fermentation. The method which is the method for producing the butyl alcohol and the succinic acid produces the butyl alcohol and the succinic acid simultaneously through fermenting microbe in different systems and gas which is produced in producing the butyl alcohol through the fermentation is inputted in a system for producing the succinic acid through the fermentation. The method connects a butyl alcohol fermentation system and a succinic acid fermentation system in series, CO2 and H2 which are produced through fermenting the butyl alcohol are utilized to promote succinic acid synthesis, which not only realizes the comprehensive use of the CO2, reduces the discharge of greenhouse gas, but also reduces the using amount of carbonate in the succinic acid producing process. The method does not need reforming complex devices and only needs adding a filtrating and removing bacteria device and then connecting with an air intake duct of a succinic acid fermentor. Experiments show that the method of the invention can keep or even increase the synthesis concentration of the succinic acid under the condition that the carbonate is not additionally added and simultaneously butyl alcohol synthesis is not affected.