After 2001, AES becomes the standard encryption algorithm, there are a lot of attacks appeared, such as differential attack and linear attack. Recently, there is a new attack named XL algorithm. It tries to change the AES into the problem of solving equations of multivariate polynomials. This method attracts many people¡¦s attention. But the method is proved wrong by Dr. Moh and Don Coppersmith. So the author of XL algorithm made some change to the algorithm and called the new method XL2 algorithm. Different from XL, XL2 can only be used in GF(2). In order to understand the efficiency of XL2, we implement the algorithm. In this paper, ¡¥Essential algebraic structure within the AES¡¦, the authors transform the AES into BES and get more equations by that. Different from BES, we transform the AES into the multivariate polynomials in GF(2) and try to solve it with our implementation of the XL2 Algorithm.