3D character animation is a very challenging field as it requires understanding of two different paradigms: fine arts and computer science. Currently there are many techniques used for animation authoring such as key framing, motion capture, non-linear editing, and forward and inverse kinematics.  A limiting factor shared between current animation techniques is that they represent animation as a series of translation and rotation without considering other important aspects such as the rational of the motion, geometrical constraints between characters acting in the scene, or even between a character and his environment. For example, "standing" on floor indicates that both feet touch and parallel to floor.  In this thesis I studied the foundations of classical and computer character animation, and then proposed using 3D geometric constraints as another method to represent animation. The method aims at capturing character's posture by a set of geometrical constraints and satisfying them using numerical methods. Maya plug-in has been implemented to build and solve symbolic geometric constraints for simple skeleton. The thesis includes a discussion on the results, usability and limitations of the proposed solution