The invention discloses a signcryption method from a certificateless environment to an identity environment and belongs to the field of secure communication. In order to enable a sending end based on the certificateless environment to send messages to a receiving end based on the identity environment through the signcryption method, the signcryption method includes the steps that after system parameters are initialized, a key generation center generates a part private key DA and sends the part private key DA to the sending end, and the sending end generates a secrete value randomly based on the system parameters, and a complete private key SA and a public key PKA are arranged with the part private key DA; a private key generation center generates a private key SB and sends the private key SB to the receiving end; the sending end generates a signcryption ciphertext according to the system parameters, the identity of the sending end, the complete private key SA, the public key PKA, the identity of the receiving end and the messages m, and the ciphertext, the identity of the sending end and the public key PKA are sent to the receiving end to conduct signcryption treatment. The signcryption method is used for signcryption communication of a heterogeneous network, and end-to-end secrete, complete, certificated and undeniable services are provided for users in the certificateless environment and users based on the identity environment.