Computational methods have been playing crucial roles in diverse fields such as mechanical, civil, electrical and electronic engineering. The Japan-China Symposium on Boundary Element Methods (1987, 1988, 1990, 1991, 1993, 1994, 1996, 1998) held in Japan and China, First Pan-Pacific Conference on Computational Engineering (PCCE93, 1993) in Seoul Korea, and the Asia-Pacific International Conference in Computational Methods in Engineering (2003 in Sapporo Japan, 2006 in Hefei China) have made substantial contribution on the computational methods. It is our great pleasure to announce that, following these successful conferences, the Third Asia-Pacific International Conference in Computational Methods in Engineering 2009 (ICOME2009) will be held in Nanjing, China to make eager discussion on recent development and exchange the latest ideas. One of the prior aims of this conference is to assimilate the newest computational methods which have independently been developed in the computational mechanics and different fields for co-evolution of different fields. Emphasis is also placed on the application of the latest approaches to computational methods, such as knowledge-based technique, machine learning, soft computing, parallel and grid computation and Web-based distributed computation which will open the door to future computer aided design.