1. A method for reconstructing a three-dimensional model, adapted to build a three-dimensional model of an object, comprising: obtaining a plurality of first depth images of the object, wherein the object is a human body; dividing the first depth images of the object into a plurality of depth image groups according to linking information of the object, wherein the linking information records location information corresponding to a plurality of substructures of the object, each of the depth image groups comprises a plurality of second depth images, and each of the substructures corresponds to the second depth images of each of the depth image groups; building a local model corresponding to each of the substructures according to the second depth images and the location information corresponding to each of the substructures; and merging the local models corresponding to the substructures according to the linking information of the object, so as to build the three-dimensional model of the object, adjusting the local models according to the features of the surface of the object, wherein the step of merging the local models corresponding to the substructures according to the linking information of the object to build the three-dimensional model of the object further comprises: in a plurality of pixels in each of the second depth images corresponding to each of the substructures, when three neighboring pixels are connected to another pixel, determining whether a first figure formed by the three neighboring pixels is overlapped with a second figure formed by two of the three neighboring pixels and the other pixel; when the first figure is overlapped with the second figure, determining a connection relationship between the three neighboring pixels and the other pixel to be incorrect; and when the first figure is not overlapped with the second figure, maintaining the connection between the three neighboring pixels and the other pixel.