Human platelet-derived growth factor-BB (hPDGF-BB), a proliferation factor, has been successfully manufactured and approved by FDA as the treatment for diabetic foot ulcer and self bone grafting. There have been no reports on the storage of the recombinant hPDGF-BB (rhPDGF-BB) in the Pichia pastoris fermentation broth although during the research of process development and the production manufacture it needs to be stored at low temperature. The concentration of rhPDGF-BB protein in the fed-batch fermentation broth of P. pastoris was stable during 3-week storage at -20 o C, but its bioactivity was reduced by 20%. The addition of a mixture of 50% glycerol with either 1 mM EDTA or 1 mM PMSF into the fermentation broth could fully preserve the bioactivity of rhPDGF-BB until 3 weeks at -20 o C. The addition of 50% glycerol with either 1 mM EDTA or 1 mM PMSF was found no affection on the protein purification process.