The invention provides a binaryzation method of a pig ear tag code figure without black hole influence. The method comprises the steps of 1) obtaining a gray level image data matrix of the pig ear tag code figure; 2) dividing the gray level image data matrix into four blocks averagely; 3) calculating a corresponding average gray level image value nAvg of 64 gray level image data of each block; 4) extracting the outermost 3 lines and 3 rows of gray level image data of the gray level image data matrix of the pig ear tag code figure, namely extracting 39 gray level image data from each sub block respectively; 5) calculating a threshold value to be binarized corresponding to each sub block, according to the 39 gray level image data of each sub block; 6) comparing all the 64 gray level image data of each sub block with the threshold value of the corresponding sub block, and completing the binaryzation of the 64gray level image data of the 4 sub blocks; and 7) combining the binaryzation of the 64 gray level image data of the 4 sub blocks. According to the binaryzation method disclosed by the invention, the influence of the black hole in a pig ear tag code on the binaryzation of the pig ear tag code figure is removed, and the binaryzation accuracy is high.