Abstract: The effect of sodium nitrite in vitro on adhesion, formation and eradication of Staphylococcus aureus ( SA) and Vibrio Parahaemolyticus ( VP) biofilm was studied by using microtiter plate assay in this paper.More information about the inhibition mechanism was gotten by cell- surface interaction assay and cells aggregation assay. The results indicated that the concentration- dependent inhibition effect of S. aureus biofilm was predominant with600 mg / L sodium nitrite added after 48 h.The bacterial biofilm clearance at this time was 37.31%.However, adding200 mg / L of sodium nitrite after 12 h of biofilm formation had the strongest V.Parahaemolyticus biofilm suppression effects with the clearance 36.67%.It was suggested by cell- to- surface interactions and cell- to- cell aggregation interaction to inhibition effect of sodium nitrite on adhesion and bacterial aggregation of S. aureus and V.Parahaemolyticus. In conclusion, sodium nitrite can restrain the formation and growth of S. aureus and V.parahaemolyticus biofilm, by influence cells aggregation and cell- surface adhesion.