1. A method for extracting a characteristic of a three-dimensional face image, performed by a computer program instructing relevant hardware, comprising: performing face area division to a three-dimensional face image, to obtain a group of face areas; projecting each face area onto a corresponding regional bounding sphere; obtaining an indication of the corresponding face area according to the regional bounding sphere, and recording the indication as a regional bounding spherical descriptor of the face area; calculating a weight of the regional bounding spherical descriptor of the face area for each face area according to values of interaction information between the regional bounding spherical descriptor of the face area and regional bounding spherical descriptors of other face areas within the group of face areas; and obtaining a characteristic of the three-dimensional face image according to the indication of each face area and the corresponding weight, wherein the characteristic includes both identity and emotion information of the three-dimensional face image; wherein the step of obtaining an indication of the corresponding face area according to the regional bounding sphere comprises: calculating a value of a point on the face area for each face area, wherein the value of the point on the face area is a ratio of a distance between the point and the sphere center of the regional bounding sphere corresponding to the face area to the radius of the regional bounding sphere; and the indication of the face area is a vector formed by values of points on the face area.