The M&A of Yageo and Philips¡¦s global passive components department in 2000 is a well-known failure case. This study investigates this 18.8 billion M&A case using business evaluation in order to explore its synergy and whether the offer price is reasonable. Contrary to media reports, this study found that the price was somehow high but reasonable during the period. Research shows taking out this M&A deal will erode shareholders¡¦ interest by NTD$31 billion. Yageo¡¦s current state of core business value is analyzed to find that Yageo¡¦s value increases at least NTD$40 billion. A decade after the M&A, Orion ¡V reinvested by Yageo Chairman Chen Taiming - announced to obtain 100% of Yageo¡¦s equity of NTD$16.1 per share in early April, 2011. Such action indicates Chairman Chen foresaw potential profitability in Yageo. In addition, the previous M&A of Philips Passive Components Division has a great influence in recent growth and points out that the M&A decision are not wrong. The findings of the study show that post-merger integration is implemented properly can gain positive benefits for shareholders through the M&A of Philips Passive Components Division.