1. A method, comprising: providing a three-dimensional (3D) human model, a plurality of vertices of the 3D human model being located at first positions; providing a 3D outfit model, a plurality of vertices of the 3D outfit model being located at second positions; in response to that the 3D human model is deformed and the vertices of the 3D human model are displaced from the first positions to third positions, adjusting the 3D outfit model corresponding to the 3D human model by setting each of the vertices of the 3D outfit model to fourth positions according to the second positions and displacements of the vertices of the 3D human model between the first positions and the third positions, wherein the step of adjusting the 3D outfit model comprises: selecting a plurality of sampled vertices from the vertices of the 3D human model according to a geometry relationship between the 3D human model and the 3D outfit model, the sampled vertices are located on a conjunction area between the 3D human model and the 3D outfit model; calculating association weights respectively for each of the vertices of the 3D outfit model by separately calculating the association weights between one of the vertices of the 3D outfit model and all of the sampled vertices on the conjunction area, wherein the association weights are negatively correlated to distances between the one of the vertices of the 3D outfit model and the sampled vertices; and calculating the fourth positions of each of the vertices of the 3D outfit model according to the second positions, the association weights and the displacements of the sampled vertices of the 3D human model between the first positions and the third positions, each one of the fourth position of the vertices of the 3D outfit model is individually calculated in related to all of the sampled vertices on the conjunction area between the 3D human model and the 3D outfit model.