This book introduces some basic knowledge and methods of analyzing and solving problems involved in the field of mechanical engineering. The book consists of 12 chapters, the main contents are: Problem solving ability training; Mechanical parts and machine tools; Structure and fluid mechanics; Materials and stresses; Heat and energy systems; Mechanical motion and mechanical design. The length is appropriate, suitable for the first and second year undergraduate students of machinery, energy, power engineering and other related majors in colleges and universities.