LDPC code and RS code are error-correcting codes which are researched much more at present, and in the two-dimensional bar code's applications the error correction code plays an important role. In order to accurately identify the two-dimensional bar code, error-correcting code's performance should be further enhanced. There is a simple introduction of the LDPC decoder based on BP algorithm and decoding algorithm for RS, and it gives MATLAB simulations in different iterations while in the same code length and code rate for LDPC code and RS code. Simulation results show that the greater the number of iterations the better the LDPC decoding performance, and the more errors can be rectified; based on the same code length and rate of the cases and less than 512 yards long, LDPC decoding performance is significantly higher than the RS code. It can be seen that LDPC code can do better than the RS codes on identifying two-dimensional bar code, and the information which we want can be reproduced clearly.