1. A global minimum searching method, comprising: clustering a subclass of a plurality of space points in a multidimensional space into a plurality of clusters through a clustering algorithm, wherein each of the space points is corresponding to an error value in an evaluation function; respectively calculating a plurality of ellipsoids for enclosing the clusters in the multidimensional space; respectively inputting a designated space corresponding to each of the ellipsoids into a recursive search algorithm to search for a local minimum among the error values corresponding to the space points within the designated space; and comparing the local minimums to obtain the space point corresponding to the minimum local minimum.