The experiments of single cell protein production were carried out from dried sweet potato production through the mixed culture by Rhizopus oligosprous AS3.4392 and Candida arborea 1.257 using airlift bioreactors without or with sieve plates. After 48h fermentation, the crude protein contents were 46.4 % in the airlift bioreactor without sieve plates, 47.1 % with one sieve plate and 47.7 % with two sieve plates, respectively. The results of experiments showed that the culture properties of the airlift bioreactors were superior to those of the mechanically agitated bioreactor. In the experiments of oxygen transfer characteristics, it was found that adding sieve plates in the airlift bioreactors could strengthen the oxygen transfer.