Grid system has secure requirements of confidential communication, data integrity and non-repudiation. According to the secure requirements for Grid service, the paper proposed an identity-based encryption scheme for Grid, which can solve a series of problem: the privacy of data transmission, validation of integrity of data, key update after long run time and non-repudiation. The scheme is constructed by bilinear paring on elliptic cures and its security can be reduced to the computational Bilinear Diffie-Hellman assumption. Finally, the authors analyses the security and efficiency of this scheme.