Data are important for making decisions. However, the quality of the data affects the quality of decisions. Data mining as one of the most important sources of knowledge needs high quality data to mine, but there are not enough good quality data in many enterprises. By analyzing the reasons for low data quality systematically, a new method called data mining consulting for improving data quality has been established. It defines data quality in a wider sense from the view of data mining, finds data quality problems, and solves data quality problems by a series of methods. Its application shows that it has good practicality and can increase data quality considerable.