In recent years, most oilfields have progressed into high water content development stage in China. Crude oil produced from these oilfields contains a number of emulsions and investigation on characteristics and properties of crude oil lactescence has become an important topic. By using experimentation, conducted is stability analysis on oil/water (O/W) emulsions produced from Bohai 26-3 Oilfield of China National Offshore Oil Cooperation and explored are dehydration effects of different demulsifiers and electric fields. Analytical investigation results show that internal phase concentration of emulsion has large effect on its stability and an optimum concentration exists in emulsion. W/0 emulsion cannot formed if internal phase concentration exceeds certain value, heavy oil W/0 emulsion behaves most stable when rotate speed is 500 r/m and the stability will decrease when rotate speed is more or less than 500 r/m.