The eighth edition of Theoretical Mechanics of Harbin Institute of Technology published by Harbin Institute of Technology Press in September 2020 was co-authored by Professor Li Desheng and Professor Chen Ping. The book introduces the basic principles and application methods of theoretical mechanics, including the law of motion, Newton's law, the law of energy, the principle of relativity and its application among multiple objects. In addition, the book also introduces the initial conditions and general solutions, such as the standard form of ordinary differential equations and the application of Laplace transform in mechanics.