The existing schemes against global wiretapping attacks for network coding have the problems of bringing bandwidth overhead and incuring high computational complexity. In order to reduce the bandwidth overhead and enhance the actual coding efficiency, a novel secure network coding scheme against global wiretapping was proposed. For the network coding with the size of field is q, two permutation sequences of length q were generated by using the key, and the source message was mixed and replaced by using the permutation sequences so as to resist global wiretapping attacks. The source message was only encrypted at the source node and had no change at the intermediate nodes. The proposed scheme has a simple encryption algorithm, low coding complexity and doesn't need pre-coding, so it doesn't bring bandwidth overhead and has high actual coding efficiency. The analysis results show that the proposed scheme can resist not only the ciphertext-only attacks but also the known-plaintext attacks efficiently.