As a new demulsifier, bio-demulsifier is explored recently to break the oil-water emulsion. In this study, one demulsifiying strain isolated from oil contanimated soil was identified as Dietzia sp. by 16S rRNA. When it was cultured in MMSW substrate, adding MWFO and SWFO as the carbon source, it could produce crude biodemulsifier of 4 g/L and 3.5 g/L respectively. Compared with biodemulsifier produced by paraffine as the carbon source, both of them could achieve higher demulsification ratio in breaking W/O and O/W model emulsion. Additionally, biodemulsifer produced by SWFO as the carbon source had the ability to demulsify two model emulsion effiectively. By analyzing the carbon utilization, it could be concluded that C16 and C18 fatty acid of the two waste frying oils were preferable for Dietzia sp.. The biodemulsifers produced from three different carbon sources all of which were identified as lipopeptide by TLC and FTIR. Further research should be taken to investigate its chemical structure.