Abstract: Due to the poor quality of injected water in Penglai Oilfield, the water injection wells are plugged quickly. In order to ensure that the oilfield is injected into enough water, a large number of wells are acidified and the cost is high. In order to reduce costs and increase efficiency, the technical level of acidizing needs to be improved continuously. According to the research, the traditional friction of acidizing is calculated according to the injection target so that the acidizing pressure of the wellhead is a definite value. In fact, the displacement of acidizing is generally larger than injection target. As a result, the calculation of friction and actual value are smaller than actual value. For this reason, the article presents a viewpoint that the acidizing friction and the acidizing pressure of the wellhead should be changed with the displacement of acidizing, which has achieved good results for acidizing of water wells in practical applications.