1. An image matching method, for performing a stereo matching from a first image block to a second image block in a stereo matching system, the image matching method comprising: performing a matching computation from the first image block to the second image block according to a first matching algorithm to generate a first matching result; performing the matching computation from the first image block to the second image block according to a second matching algorithm to generate a second matching result; performing the matching computation from the second image block to the first image block according to the second matching algorithm to generate a third matching result; obtaining a matching error of the first image block corresponding to the second matching block according to the second matching result and the third matching result, and obtaining a matching similarity of the first image block matched to the second image block according to the second matching result; and determining a stereo matching result of the first image block as the first matching result or the second matching result according to the matching error and the matching similarity.