As an important automatic identification technology, the two-dimensional bar code has wide range of prospects for commercial applications. Effective solution of the two-dimensional bar code image blur is the key to its wide use. In order to recognize the blurring type, an algorithm based on invariant moment theory is proposed. The frequency spectrum in different types of degradation for blurred bar code images is analyzed to find their differences. After edge detection, denoise processing and binarization , the invariant moment feature is extracted to recognize the blurring type. Experimental results show that the proposed algorithm can obtain a high recognition rate.