In order to improve efficiency of excavation in relational database with multi-dimensional association rules, this paper analyzed Apriori algorithm and BUC algorithm based on practice. Then an improved Apriori algorithm-DGP algorithm which based on the multidimensional association rule was presented, it has more efficient and it will be used in the relational database. At last it was applied for analyzing the reasons for users’ line which not reach the standard. It can improve the speed of Data mining effectively, enhance the ability of ADSL line quality’ s analyzing and solving.