The study examined the relation of the under-pricing in seasoned equity offering (SEO) firms between the corporate governance and the rank of the underwriters. The SEO sample in the study is between 1991 to 2007 in Taiwan Exchange. The results show that the ranking of underwriters has a positive association with post-SEO three-year abonrmal return, that means the underwriters have “Certification effect” for SEO firms. Second, the more pre-SEO decrease of insiders’ shareholding has higher under-pricing, these phenomenon conforms our third resust about the firms with more agency problem. Finally, the SEO frms prefer to rising capital when the market overvalued.