Abstract: In view of poor waterflood and unsatisfactory acidizing effect in Zhaowa block in Henan oilfield, analysis of adverse reservoir factors and research of acid stimulation technology have been carried out The optimization of acid fluid system shows that the optimized acid fluid has little corrosive attack towards metal as well as strong dissolution ability towards debris and it is in good matching with underground fluid. Three field experiments were carried out, achieving an effective successful rate of 100% and decreased injection pressure of 1 - 8MPa.