1. A method for producing a 3D facial animation using a single facial video stream, comprising: producing a representative joint focused on a major expression producing element in a 3D standard facial model; producing a statistical feature-point model of various facial expressions of different people in the 3D standard facial model; moving each feature-point of the statistical feature-point model by tracking a change in facial expressions of the video stream; calculating a transformation coefficient of the representative joint corresponding to a variation of the feature-point of the 3D standard facial model; and producing a 3D facial animation by applying the calculated transformation coefficient to transform the representative joint.