AES is one of the most widely used cryptographic systems. DNA computing has the high efficiency to solve some NP-problems. Therefore many scientists try to combine DNA computing with cryptography. In this paper, an algorithm is designed to simulate a plaintext encrypted by DNA biotechnology and modern cryptography. After mapping the plaintext information as DNA chain and handling the base chain with biological genetic technology, we can get the gene codes form, then using the Rijndael algorithm to deal with the biological chain with cryptography and get the final result. It makes the DNA-based cryptography more effective and more security.