Abstract: Acidification will produce some insoluble materials which will plug the pore throats and bring new damage on oil reservoirs.This phenomenon is called acid-sensitivity.In order to provide materials for acidizing fluid and acidification, the acid-sensitive analysis is conducted.It is experimented that the mud acid sensitivity is strong or too strong in the east section of No.1 structure of Nanpu Oilfield in the way of 34 drill cores.This result is related to the permeability, the total content of clay, the content of different clay mineral and acid concentration.it is easy to cause acid-sensitive damage in high permeability zones. There are many factors which will influence the acid-sensitive formation damage in the high mineral co res. The higher the concentration of HF acid is, the greater the acid-sensitive format ion damage is.The main reasons for strong acid sensitivity in the east section of No.1 structure of Nanpu Oilfield is that the overdissoluted cements, which have caused the breaking structure of rock, the migration of particles blocked seepage pore and decreasing permeability.It is very important to use proper acid systems and proper concentration to increase production in the acid-sensitive reservoirs.