There are a lot of security issues in block cipher algorithm.Security analysis and enhanced design of an dynamic block cipher was proposed.Firstly, the safety of ciphertext was enhanced based on confusion substitution of S-box, thus disordering the internal structure of data blocks by four steps of matrix transformation.Then, the diffusivity of ciphertext was obtained by cyclic displacement of bytes using column ambiguity function.The dynamic key was finally generated by using LFSR, which improved the stochastic characters of secret key in each of round of iteration.The safety performance of proposed algorithm was analyzed by simulation test.The results showed the proposed algorithm has a little effect on the speed of encryption and decryption while enhancing the security.Meanwhile, the proposed algorithm has highly scalability, the dimension of S-box and the numer of register can be dynamically extended according to the security requirement.