Theoretical mechanics is a subject that studies the basic laws of mechanical motion of objects. A branch of mechanics. It is the basis of all branches of general mechanics. Theoretical mechanics is usually divided into three parts: statics, kinematics and dynamics. Statics studies the simplified theory of force system acting on objects and the equilibrium conditions of force system; Kinematics only studies the mechanical motion characteristics of objects from the geometric point of view, and does not involve the force of objects; Dynamics studies the relationship between mechanical motion and force. Dynamics is the core of theoretical mechanics. The research method of theoretical mechanics is based on some basic axioms or laws that reflect objective laws induced by experience or experiments, and the mechanical motion laws of objects in general and the characteristics of specific problems are obtained through mathematical deduction. Objects in theoretical mechanics mainly refer to particles, rigid bodies and rigid body systems. When the deformation of an object can not be ignored, it becomes the object of discussion in deformation mechanics (such as material mechanics and elastic mechanics). Statics and dynamics are the main parts of engineering mechanics.

Theoretical mechanics establishes scientific and abstract mechanical models (such as particles and rigid bodies). Both statics and dynamics are related to the physical cause of motion-force, which is collectively called kinematics. Some literatures confuse dynamics and dynamics as synonyms. Both of them can be translated into dynamics, or one of them can be translated into motion mechanics. In addition, combining kinematics and dynamics, theoretical mechanics is divided into statics and dynamics.

Theoretical mechanics is based on some basic concepts, axioms and laws that reflect the basic laws of ideal object motion. For example, statics can be derived from five statics axioms; Dynamics is based on Newton's laws of motion and gravity. Another feature of theoretical mechanics is the extensive use of mathematical tools for mathematical deduction, thus deriving various general theorems and conclusions expressed in mathematical form.