Aiming at the problem of information security，an encryption system to encrypt information is proposed. On the basis of the close connection between chaos and cryptography ，first，a chaotic dynamic polluted system is constructed，and then an algorithm of sequence encryption is carried out.Introducing a pollution factorα，a polluted chaotic mapping is constructed based on segmented nonlinear and parabolic mapping，then an algorithm of encryption is executed by giving constantly changing parameter values，that is，the results of the previous round in the system affect the initial value of the next round，so that the system is a tight whole. And ciphertext is obtained. Finally ，the effectiveness of this encryption algorithm is verified by correlation，sensitivity，and frequency test. Results show that the encryption algorithm has a good encryption effect，both ciphertext and algorithm can effectively resist attacks.