The term “Tree of Life” was first used by Charles Darwin in 1859 as a metaphor for describing phylogenetic relationships among organisms. Over the past three decades, the recognized tree of life has im- proved considerably in overall size and reliability due to an increase in diversity of character resources, a dramatic growth in useable data, and the development of tree-reconstruction methods. As a bridge connecting phylogeny, evolution and related disciplines, such as molecular biology, ecology, genomics, bioinformatics and computer science, the tree of life is increasingly widely used. In this paper, we review the history and progress of tree of life studies and focus on its application in the following fields: (1) the reconstruction of phylogenetic trees at different taxonomic hierarchies to understand phylogenetic relationships among taxa; (2) investigation of the origins of taxa and biogeographic patterns based on dating estimation and bio- geographic reconstruction; (3) examination of species’ diversification and its causes by integrating dated trees, ecological factors, environmental variation and key innovations; (4) the study of the origin and patterns of biodiversity, predating biodiversity dynamics, and development of conservation strategies. Finally, we evaluate the difficulties from matrix alignment, gene tree incongruence and “rogue taxa” distraction in tree reconstruction due to massive increases of useable data and in the context consider “supertree” building in the future.