1. An automatic detection method for defects of a display panel, comprising: acquiring a tag image, a mapped original image and a mapped tag image; dividing the mapped original image into a plurality of mapped original sub-images, and dividing the mapped tag image into a plurality of mapped tag sub-images; acquiring a normal area and a defective area of the mapped original sub-images; merging the mapped original sub-images to discriminate the normal area and the defective area of the mapped original sub-images; correcting the discriminated normal area and the discriminated defective area of the mapped original sub-images by using the mapped tag image and the tag image to acquire a defect location of the display panel.