The audit of Public Enterprises by the National Audit Office (NAO) of Taiwan, has put more emphasizes in performance audit in recent years. The subjects of audit have also been changed from business management to public issues. In March 2012, Taiwan decided to raise electricity price. This policy brings alone the price raising and the complaint of people. The public queried some unreasonable things about purchasing electric power from cogeneration companies and independent power producers. The article will introduce the connotation of performance audit then will take electricity purchase of Taipower Company as an example to introduce the practice and result of public enterprises performance audit in Taiwan.