Doosan is the oldest company in Korea, and it now focuses on business in support infrastructure. Throughout its 120 years of history, Doosan had to make a number of strategic decisions to survive in an evolving economy. Traditionally, Doosan was a company that focused on domestic food manufacturing and retail in the Korean market. However, after the Asian economic crisis, the company decided to change its main business model and try its new global growth strategy. In order to achieve a rapid overseas expansion, Doosan expanded their business into heavy industry and construction with clear Mergers & Acquisitions (M&A) strategies. Now Doosan’s revenue grew from 3,400 billion Korean won (KRW) to 18,960 billion KRW. Furthermore, in 2015, 64% their revenue come from overseas, compared to 12% in 1998. In 2009, one of main Doosan company, Doosan Heavy Industries & Construction was ranked fourth among the BusinessWeek’s “World Best 40 Companies”. Doosan decided in a fast growing strategy with cross-border M&A and focused on building a new organizational culture as PMI (Post Merger Integration). This case examines how Doosan is successfully growing in the global market through cross-border M&A strategies and how it is preparing for its next hundred years.