This study presents a case study demonstrating the application of Six Sigma (DMAIC) to successfully reduce the number of online petitions on the e-petition system in Taiwan Power Company (TPC). First, in the define (D) stage, a total of 1,292 petitions for the year 2010 in TPC are received and divided into 9 categories. In the measure (M) stage, the category that received the most petition letters is "line removal", which accounts for 29.3% of the total petitions. The analyze (A) stage indicates that TPC did not provide relevant application procedures for "line removal" service. In the improve (I) stage, this study presents three approaches to speed up the "line removal" application process. Finally, a well-organized standard of procedure and workflow control charts has been developed in order to monitor the overall application and construction processes in the control (C) stage. After implementing Six Sigma (DMAIC), the number of petitions for "line removal" decreased by 66% from 379 in 2010 to 129 in 2011.