1. A method for creating a face replacement database by using a method for estimating the 3D vector angle from a 2D face image, wherein the method for estimating the 3D vector angle from a 2D face image comprises the steps of: creating a feature vector template including a feature vector model of a plurality of different rotation angles; detecting a corner of eye and a corner of mouth in a face image to be processed, and defining the corners of eye and the corners of mouth as vertices of a quadrilateral respectively; defining a sharp point in a vertical direction of the quadrilateral plane, and converting the vertices into 3D coordinates, wherein the sharp point and the vertices of the quadrilateral form a quadrangular pyramid; computing the four vectors from the sharp point to the four vertices whose coordinates are 3D coordinates to obtain a vector set, and matching the vector set with the feature vector model to obtain an angle which has the shortest distance between a feature vector model and the vector set, and defining the angle value as a rotation angle of the input face image; wherein the method for creating a face replacement database comprising the steps of: creating a face database for storing a plurality of replaced images with a face image rotation angle by using the method for estimating a 3D vector angle from a 2D face image, and defining a region to be replaced in the replaced image.