This book highlights the doctoral research of the author on electronic band structure engineering and ultrafast dynamics of Dirac semimetals. Dirac semimetals exhibit unique electronic band structure and novel physical properties with rich light-matter interaction, which inspires a wide range of potential applications. Enabling band engineering and revealing ultrafast dynamics of Dirac semimetals is therefore important. In the research work covered by the book, the first ultrafast time- and angle-resolved photoemission spectroscopy with tunable probe photon energy is developed, providing...