In this paper,we propose a new one-time one-key encryption algorithm based on the ergodicity of a skew tent chaotic map.We divide the chaotic trajectory into sub-intervals and map them to integers,and use this scheme to encrypt plaintext and obtain ciphertext.In this algorithm,the plaintext information in the key is used,so different plaintexts or different total numbers of plaintext letters will encrypt different ciphertexts.Simulation results show that the performance and the security of the proposed encryption algorithm can encrypt plaintext effectively and resist various typical attacks. In this paper, we propose a new one-time one-key encryption algorithm based on the ergodicity of a skew tent chaotic map. We divide the chaotic trajectory into sub-intervals and map them to integers, and use this scheme to encrypt plaintext and obtain ciphertext.In this algorithm, the plaintext information in the key is used, so different plaintexts or different total numbers of plaintext letters will encrypt different ciphertexts. Simulation results show that the performance and the security of the proposed encryption algorithm can encrypt plaintext effectively and resist various typical attacks.