This book introduces some basic knowledge involved in the field of mechanical engineering and the methods of analyzing and solving problems. The book consists of eight chapters, the main contents of which are: the cultivation of problem-solving ability; Mechanical parts and machine tools; Structure and fluid mechanics; Materials and stresses; Thermal energy system; Mechanical movement and mechanical design. After each chapter, there are various types of exercises for students to think and practice, and the length is appropriate, which is suitable for freshmen and sophomores majoring in mechanical, energy and power engineering in Chinese universities.