Abstract: Investigations on acid distribution of Sudan crude and on thermal cracking acid-removing technology were conducted in the lab-scale and pilot plant devices. The technology developed was commercialized in Sudan refinery. The results show that high temperature and high circulation ratio can improve deacid efficiency, the acid removal reaches above 98% at the temperature about 500 ℃ and circulation ratio of the feed to gas oil about 0.3. The technology developed and applied in Sudan refinery for processing high TAN heavy crude has crude atmospheric distillation and delayed coking functions besides acid–removing. The commercial results show that the deacid rate is about 91%, the liquid yield and light oil yield reaches 80% and 64.31% respectively, the total acid number(TAN) of products drops sharply.