DNA computing is a new method of simulating biomolecular structure of DNA and computing by means of molecular biology technological computation. It introduces a fire-new data structure and calculating method, providing a new way for solving the NP-complete problem. It is a new computational method by harnessing the enormous parallel computing ability and high memory density of bio-molecules, which brings potential challenges and opportunities to traditional cryptography. DNA cryptography is a new field of cryptography arising with DNA computing research in recent years. It can realize several security technologies such as Encryption, Steganography, Signature and Authentication by using DNA molecular as information medium. We firstly introduce the basic idea of DNA computing, and then discuss the information security technology in DNA computing.