Microorganisms were screened from garden soil and pickles to meet the requirements conditions for the wet corn starch process,which are at 50℃ and pH3.5~5.We did identification of morphological and molecular biology of the microorganisms.The microorganism was initially identified as Aspergillus fumigatus(A.fumigates strain).We studied the enzyme properties of crude enzyme of acid protease extracted from the fermentation broth,and the results suggested that the crude enzyme still maintained a high stability at 50 ℃ and pH 3.5~5.The fermentation broth was applied in the production of corn starch to optimize the conditions of corn soaking.The optimum soaking conditions for corn steeping processing were: steeping water temperature 50℃,lactic acid 0.5%,SO2 0.08%,initial immersion 12h,add 12% soaking broth 10h.The technology can reduce environmental pollution,short soaking time of 26h,so it is more conducive to apply to the industry production.