1. A method for binarizing a two dimensional code image, the method comprising: dividing the two dimensional code image into a plurality of block regions; obtaining grayscale values of all pixels in each block region, and obtaining a grayscale value for each block region according to the grayscale values of all the pixels; determining for each block region a grayscale threshold of the block region according to an average grayscale value of a predetermined area where the block region locates; binarizing pixels in the block region according to a grayscale threshold corresponding to each block region; wherein the process of determining for each block region a grayscale threshold of the block region according to an average grayscale value of a predetermined area where the block region locates comprises: obtaining an average value of the grayscale values of multiple block regions included in the predetermined area as the grayscale threshold according to grayscale values of the multiple block regions.