Theoretical Mechanics is a core foundational textbook for undergraduate students in civil engineering, mechanical engineering, and related disciplines. Based on a systematic review of classical mechanics theories and years of teaching reform experience, this book aims to achieve an organic integration of knowledge transmission, skill development, and modern teaching methods. It features three main highlights: First, it adopts a student-centered approach, providing chapter task lists and QR-code-linked micro-videos to support discussion-based and blended learning. Second, it ensures rigorous exposition and standardized problem-solving, with multi-level thought questions and diverse exercise types to strengthen conceptual understanding and comprehensive problem-solving skills. Third, it integrates classical theory with cutting-edge developments and international engineering cases, fostering students' innovative thinking, engineering insight, and global perspective. Suitable for both self-study and various classroom models, this textbook serves as an effective tool for theoretical mechanics instruction.