1. A global minimum searching method, comprising: executing a plurality of steps by a computing apparatus, wherein the steps comprise: 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 each designated space corresponding to each of the plurality of ellipsoids into a recursive search algorithm to search for a local minimum among the error values corresponding to the space points within the each designated space; and comparing the local minimums of the plurality of ellipsoids to obtain the space point corresponding to the minimum of the local minimums.