Succinic acid in simulated fermentation broth extracted by complexaion extraction was studied.The mixed solvent with 30% TOA+ 40% octanol+ 30% methylbenzene can give a high distribution coefficient for succinic acid when succinic acid was undissociated form.The distribution coefficient reduced when succinic acid or SO42-concentration increased.The extraction yield of succinic acid for simulated fermentation broth reached 82%,the extraction capacity of succinic acid was 39.5g/L,1.0 mol/L of NaOH was stripping agent,the stripping yield can reach 96%.On this basis,succinic acid in fermentation broth extracted by complexation extraction was studied.The extraction yield of succinic acid of low succinic acid concentration fermentation broth reached 96.7%,the stripping yield reached 98.9%;the extraction yield of succinic acid of high succinic acid concentration fermentation broth reached 70.6%,the extraction capacity of succinic acid was 40.5 g/L,the stripping yield reached 84.6%.The succinic acid could be separated by the complexation extraction,especially for low succinic acid concentration fermentation broth.