There are many drawbacks in current encryption algorithms in respect of security, real-time performance and so on, and researchers are presenting various algorithms. Among them, the elliptic curve cryptography (ECC) is evolving as an important cryptography, and shows a promise to be an alternative of RSA. Small size, high security and other features characterize ECC. Based on the theory of ECC, This work analyzes its advantages over other cryptographies and focuses on its principle. A practical application implemented by Java is also presented. At last, some future works in ECC are indicated.