These proceedings contain the written versions of most of the invited talks presented at the Sixth International Conference on Atomic and Molecular Data and Their Applications (ICAMDATA), held in Beijing, China, October 27-31, 2008. As a continuing series of international conferences, ICAMDATA promotes the use of atomic and molecular (AM) data in various fields of science and technology, provides a forum for interaction of AM data producers and users. These proceedings cover the topics of atomic and molecular physics and data production, new data format, and data applications and needs in wide relevant fields such as astrophysics and astronomy, magnetic and inertial fusions, low temperature laboratory plasmas and industry plasmas, atmosphere biophysics. They presented the state of the art and provided rich information on atomic and molecular data needs, applications and availability, and modeling studies.