A person re-identification method, a person re-identification system and an image screening method are provided. The person re-identification method includes the following steps. A plurality of identified images of an identified person are analyzed to obtain an interrelated array, which records a plurality of degrees of association among the identified images. The interrelated array is converted to a directed graph having at least one connected group. A representative path of each connected group is obtained. According to each representative path, a part of the identified images are outputted as at least one representative image set for performing a person re-identification process on an image to be identified.
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