The invention relates to a wafer pre-locating device based on machine vision and a method thereof. The device comprises a vacuum-absorbing type wafer feeding table, an image collecting and processing unit, a large-format infrared face area light source and a two-dimension micro-motion platform system. The method comprises the steps of feeding wafers, collecting images of the wafers extracting edges fitting circle centers of the wafers and adjusting positions of the wafers. The device and the method avoid damage to the edges of the wafers, and have the advantages of being free of any adjustment and capable of meeting requirements for accurate location of the wafers. Meanwhile, the device is simple in structure, low in cost, and capable of meeting requirements of manufacture of IC equipment for pre-location of the wafers.