Concerning the broadcast encryption security problem in reality, a new identity-based anonymous broadcast encryption scheme in the standard model was proposed. In a anonymous broadcast encryption scheme, broadcaster sent encrypted data to the user via a broadcast channel, which only authorized users could decrypt and access the data; meanwhile, no one knew whom the encrypted data was sent to. Thereby the recipient user's privacy was protected. The scheme was proposed by combining with dual system encryption and composite-order bilinear groups. Based on static assumptions, the proposed scheme is chosen plaintext secure in the standard model, the ciphertext and private key in the scheme has fix length. Compared with the contrast scheme, the length of key is only two group elements, and the proposed scheme can satisfy the anonymity.