Acidification heavy oil from Tahe Oilfield is emulsified seriously and has many impurities, it is difficult to apply conventional thermochemical settling dehydration process due to its high concentration chemicals, long processing time, large repeated processing quantity and poor stability of the system and it is hard to meet the production requirements. Through technical transformation, ultrasonic demulsification dehydration unit is added in the dehydration process, dehydration efficiency and effectiveness are improved significantly, dehydration time is shortened greatly, tank bottom emulsion layer thickness is reduced obviously, repeated processing quantity has fallen sharply and system stability is improved substantially. Field application shows that ultrasonic demulsification dehydration plant has a significant role in improving acid demulsification dehydration effect of heavy oil in Tahe Oilfield.