1. An iterative matching method for partial fingerprint verification, comprising: providing a plurality of database features; providing a plurality of input features; performing initial feature matching to initially compare the input features with the database features using one of the database features as a first reference point, resulting in initial matched feature pairs between initial matched database features and corresponding initial matched input features; and performing progressive feature matching to progressively compare the input features with the database features using a gravity center of the initial matched database features as a second reference point, resulting in progressive matched feature pairs between progressive matched database features and corresponding progressive matched input features; wherein the step of performing the progressive feature matching is iteratively performed unless a number of the progressive matched feature pairs is not greater than a number of the initial matched feature pairs or a number of the progressive matched feature pairs obtained in a previously performed progressive feature matching.