The invention relates to an elliptic curve cryptosystem based on an identity. The system comprises a pseudo public key, a pseudo digital certificate, an ECC key generation system, a pseudo digital certificate issuing system, a pseudo digital certificate issuing client-side, a crypto module and a crypto application program. According to the cryptosystem, the pseudo public key corresponding to one identity corresponds to an ECC public key set and an ECC private key set corresponding to the same identity in the crypto module, and therefore the crypto operation of the pseudo public key is automatically transformed into the operation of using a corresponding public key in the corresponding ECC public key set. The crypto operation of using a private key corresponding to the pseudo public key is automatically transformed into the operation of using a corresponding private key in the corresponding ECC private key set. When no corresponding ECC public key or private key exists, the corresponding ECC public key or private key is automatically acquired through the crypto module. The cryptosystem has part of advantages of an IBC, the crypto operation is easier than that of the IBC, the support of client-side crypto hardware is easily obtained, and the intervention of a user in the key updating process can be reduced.