Concerning the problems of the existing network coding schemes against global wiretapping attack such as large amount of computation, low bandwidth efficiency and low security, a secure network coding scheme by double encryption based on chaotic sequences was proposed. Firstly, a key was used to encrypt the last dimensional transmission data and the chaotic sequences were disturbed by the data itself while encrypting. Then, another key and a random number key were used to generate coding coefficient matrix, while the chaotic sequences were disturbed by m sequence. Finally, the obtained coding coefficient matrix was used for the linear combination of encrypted messages and unencrypted messages against global wiretapping attacks. Since the coding coefficient matrix was generated by the keys, the coding coefficients were not needed to be transmitted in the channel. Compared with the traditional Secure Practical Network Coding (SPOC) scheme, the proposed scheme saves the bandwidth overhead of the transmission of coding coefficients in the network. The analysis and experimental results show that, the proposed scheme improves the safety performance of network, which ciphertext-only attacks and known plaintext attacks can all be resisted. And the proposed scheme can also improve the transmission efficiency, and its algorithm complexity is moderate.