Abstract: In the Daqing oil field,the percentage of water content of crude increases steadily with increasing depth of production,reaching as high as 60% in some parts.This paper reviews a new technique of dehydration by section with the application of thermal chemical precipitation and direct currentchemical dehydration.The Daqing crude is paraffin-based,with wax content 28.7%,wax melting point 49℃,freezing point 26℃,viscosity 23.79 cp at 50℃,ashlzaltene content 0.1-0.3%,naphthenic acid 0.02-0.08,gravity 0.86.These proherties constitute the causes of forming water-in-oil emulsion which makes dehydration difficult.Application of thermal-chemical precipitation may reduce the water content of crude,but not to the point of less than 0.5% as required for export.Therefore,it should be sulap lemented by electric-chemical dehydration.Mention is made of the use of new emulsion breaker,chemical pipeline deruulsion,automatic silicon controlled voltage regulation,silicon controiled rectifier,automatic water drain of differential current etc,to reduce the water content of oil to under 0.3%,and the oil content of waste water to under 0.5% to satisfy the re